Idea Transcript
Geotechnical Foundation Investigation Report for the Saskatchewan Metals Processing Plant Project
Prepared for: Fortune Minerals Limited
Submitted by:
M2112-2840010 June 2010
Fortune Minerals Ltd. SMPP Project - Geotechnical Foundation Investigation Report
June 2010
Executive Summary General Objectives of Investigation The scope of work was to complete a geotechnical investigation for the proposed Saskatchewan Metals Processing Plant (SMPP) project in the Rural Municipality of Corman Park, No. 344, Saskatchewan. This report presents the results of the site investigation and geotechnical recommendations related to the project. Fieldwork and Laboratory Testing The drilling of eight (8) boreholes and excavation of sixteen (16) test pits were conducted between February 2010 and April 2010. Field testing was conducted and soil samples were collected during drilling. Field standard penetration tests (SPT) and pocket penetrometer tests were conducted in the boreholes during drilling. Ground resistivity tests were conducted at the future power substation location. Geotechnical laboratory tests on collected soil samples were conducted at the MDH soil laboratories in Saskatoon, Saskatchewan. These tests included grain size distributions, water contents, Atterberg limits, consolidation, Group Index, unconfined compression test and direct shear tests. Detailed salinity testing was conducted by ALS Laboratories of Saskatoon, Saskatchewan on soil samples from selected depths. One Casagrande style piezometer was installed in the study area at an approximate depth of 8.2 m (27.0 ft) to collect shallow groundwater information for foundation design. Geotechnical Foundation Report A general description of the soils encountered, the soil properties, anticipated behaviour of soils during construction and measured groundwater levels are provided in this report. Geotechnical recommendations for shallow foundations, grade supported slabs, pile foundations and other general geotechnical engineering parameters related to the plant building foundation are provided in this report. The foundation design parameters were derived from calculations based on the Canadian Foundation Engineering Manual and other relevant geotechnical references.
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Fortune Minerals Ltd. SMPP Project - Geotechnical Foundation Investigation Report
June 2010
Table of Contents 1.0 Introduction .................................................................................................................................................1 2.0 Site Condition and Description ....................................................................................................................1 3.0 Scope ..........................................................................................................................................................1 3.1 Field Investigations .................................................................................................................................1 3.2 Laboratory Testing ..................................................................................................................................2 3.3 Report .....................................................................................................................................................2 4.0 Methodology................................................................................................................................................4 4.1 Field Investigations .................................................................................................................................4 4.1.1 Geotechnical Boreholes ..................................................................................................................... 4 4.1.2 Geotechnical Test Pits ....................................................................................................................... 5 4.1.3 Standpipe Piezometer Installation and Shallow Groundwater Regime .............................................. 6 4.2 Laboratory Testing ..................................................................................................................................7 4.2.1 Geotechnical and Index Soil Properties ............................................................................................. 7 4.2.2 Unconfined Compression Test ........................................................................................................... 7 4.2.3 Oedometer / Consolidation Test ......................................................................................................... 8 4.2.4 Direct Shear Test ............................................................................................................................... 8 4.3 Undrained Shear Strength, su .................................................................................................................9 4.4 California Bearing Ratio, CBR ................................................................................................................9 4.5 Chemical Laboratory Investigation ........................................................................................................10 5.0 Subsurface Condition ................................................................................................................................11 5.1 Local Geology .......................................................................................................................................11 5.1.1 The Surficial Stratified Deposits (SSD)............................................................................................. 12 5.1.2 The Battleford Formation .................................................................................................................. 12 5.1.3 The Floral Formation ........................................................................................................................ 12 5.1.4 Upper Floral Aquifer (Dalmeny Aquifer) ........................................................................................... 13 6.0 Ground Resistivity Test .............................................................................................................................13 7.0 Geotechnical Recommendations ..............................................................................................................13 7.1 General .................................................................................................................................................13 7.2 General Site Grading, Clearing, and Site Preparation ..........................................................................13 7.2.1 General Site Grading and Clearing .................................................................................................. 13 7.2.2 Permanent Cut Slopes ..................................................................................................................... 14 7.2.3 Fill Slopes ......................................................................................................................................... 14 7.3 Temporary Excavation and Dewatering ................................................................................................15 7.3.1 Temporary Cut Slope for Excavation................................................................................................ 15 7.3.2 Utility Trench Excavation .................................................................................................................. 15 7.3.3 Foundation Excavations ................................................................................................................... 15 7.3.4 Soil and Material Stockpiling Near Excavation ................................................................................. 16 7.3.5 Temporary Dewatering ..................................................................................................................... 16 7.4 Site Surface Drainage ...........................................................................................................................16 7.5 Subgrade Preparation ...........................................................................................................................16 7.5.1 General............................................................................................................................................. 16 7.5.2 Proof Rolling ..................................................................................................................................... 17 7.5.3 Roadways......................................................................................................................................... 17 7.6 Fill Placement and Compaction ............................................................................................................18
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7.6.1 Fill Materials ..................................................................................................................................... 18 7.6.2 General/Common Fill ....................................................................................................................... 19 7.6.3 Structural fill...................................................................................................................................... 19 7.6.4 Road base ........................................................................................................................................ 20 7.6.5 Underground utilities bedding ........................................................................................................... 20 7.6.6 Utilities trench backfill ....................................................................................................................... 20 7.7 Procedures to Mitigate Frost Action in Buried Utilities ..........................................................................20 7.8 Lateral Earth Pressure Coefficients ......................................................................................................21 7.9 Frost Penetration Depth ........................................................................................................................24 7.10 Foundations ..........................................................................................................................................24 7.10.1 Shallow Foundations ........................................................................................................................ 24 7.10.2 Grade Supported Floor Slabs ........................................................................................................... 26 7.10.3 Pile Foundations............................................................................................................................... 27 7.10.4 Frost Action and Foundations........................................................................................................... 29 7.11 Seismic Design Ground Motions ...........................................................................................................29 7.11.1 Seismic Considerations .................................................................................................................... 29 7.11.2 Site Soil Classification ...................................................................................................................... 30 7.11.3 Site Spectral Acceleration ................................................................................................................ 30 7.11.4 Uniform Hazard Spectra ................................................................................................................... 30 7.12 Modulus of Vertical Subgrade Reaction, ks ...........................................................................................31 7.13 Modulus of Horizontal Subgrade Reaction, kh ......................................................................................31 7.14 Foundation Concrete ............................................................................................................................32 7.15 Paved Areas .........................................................................................................................................32 7.15.1 Pavement Subgrade Strength .......................................................................................................... 32 8.0 Construction Control and Monitoring .........................................................................................................33 9.0 Closure ......................................................................................................................................................34 10.0 References ................................................................................................................................................35 Terms, Symbols, and Abbreviations Appendices Appendix A – Site Plans Appendix B – Borehole Logs Appendix C – Ground Resistivity Test Results Appendix D – Laboratory Testing Results Appendix E – Occupation Health and Safety - Excavation
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List of Tables Table 4.1 – Borehole and test pit summary. .............................................................................................................6 Table 4.2 – Groundwater monitoring records. ..........................................................................................................7 Table 4.3 – Summary of unconfined compression strength results. .........................................................................8 Table 4.4 – Summary of consolidation test results. ..................................................................................................8 Table 4.5 – Summary of direct shear test results. ....................................................................................................9 Table 4.6 – Average undrained shear strengths of soil at various depths. ...............................................................9 Table 4.7 – Summary of calculated CBRs results. .................................................................................................10 Table 4.8 – Summary of soil porewater chemistry results. .....................................................................................11 Table 7.1 – Base and sub-base gradation specifications. ......................................................................................21 Table 7.2 – Lateral earth pressure coefficients and soil unit weights. ....................................................................21 Table 7.3 – Typical compaction equipment data for estimating compaction-induced loads. ..................................23 Table 7.4 – Calculated frost penetration depth under various surface covers. .......................................................24 Table 7.5 – Ultimate and allowable bearing capacity for shallow foundations. .......................................................25 Table 7.6 – General design parameters for bored, cast-in-place pile foundations. ................................................27 Table 7.7 – Typical group efficiency for 3x3 and 9x9 pile groups (After NAVFAV 7.02)......................................... 29 Table 7.8 – Damped spectral acceleration for 2% probability of exceedance in 50 Years. ....................................30 Table 7.9 – Group reduction factor for modulus of horizontal subgrade reaction, kh. .............................................32 List of Figures Figure 7.1 – Horizontal pressure on walls induced by compaction effort. ..............................................................23 Figure 7.2 – Estimated settlement vs. applied presure for various sized square footing found at 10 ft below ground. ..........................................................................................................................................................26 Figure 7.3 – Uniform hazard spectrum for 2% probability of exceedance in 50 Years. ..........................................31
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1.0 Introduction MDH Engineered Solutions Corp. (MDH) was commissioned by Fortune Minerals Limited (Fortune Minerals) to provide geotechnical, hydrogeological and environmental services in support of the design and construction of the Saskatchewan Metals Processing Plant (SMPP) project in the Rural Municipality of Corman Park, No. 344, Saskatchewan. The work described in this report is for the Geotechnical Investigation for Foundations Analysis (Task 2) given in the workplan submitted to Fortune Minerals by MDH in February 2010. The proposed site area for the SMPP project is located in Sections 14 and 23 of Township 39, Range 7, approximately 2.5 km east of the community of Langham and 30 km northwest of Saskatoon. The site location plan is presented in Figure A1 in Appendix A and the facility Site Plan is shown on the Figure A2 in Appendix A. This report provides geotechnical recommendations for foundations and other geotechnical considerations related to the construction of the plant buildings and rail line.
2.0 Site Condition and Description Fortune Minerals’ SMPP project site is currently cultivated farmland which is relatively flat. The existing ground elevations within the future plant buildings area ranged from approximately 521 meters above sea level (masl) to 523 masl. The steepest local ground gradient is approximately 1V:30H. A topographical survey map of the project area is shown on Figure A3 in Appendix A. The project area is located approximately 1 km to the north of Highway 305. An existing rail track runs through the site from the south in southeast-northwest direction.
3.0 Scope The general scope of this geotechnical investigation was to complete a geotechnical evaluation for the site in support of foundation designs for the plant buildings and related geotechnical engineering work.
3.1 Field Investigations The general scope of this investigation was to complete a surface geotechnical evaluation of the SMPP project site. The detailed scope of the investigation was to: 1) Drill at eight (8) locations within the vicinity of the plant site to depths of approximately 24 m (80 ft) the purposes of geotechnical testing and sampling.
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2) Install one (1) Casagrande style standpipe piezometers at the plant site location to an approximate depth of 8.2 m (27 ft) to determine shallow groundwater levels. 3) Excavate sixteen (16) test pits to 3.0 m (10 ft) in depth to gather disturbed soil samples and to complete field and laboratory testing. 4) Carry out a Wenner 4-pin soil resistivity test at a variety of probe spacings (up to maximum 3.0 m (10 ft)) to provide recommendations for building grounding and cathodic protection for concrete reinforcement and other buried metal structures vulnerable to chloride induced corrosion.
3.2 Laboratory Testing Complete a suite of geotechnical index testing on select samples acquired from the boreholes and test pits including: 1) 2) 3) 4) 5) 6) 7) 8) 9)
Atterberg limits; Unconfined compression tests; Water soluble sulphate; Water content; Grain size analysis including hydrometer; Specific gravity; Group index; Consolidation tests; and, Direct shear tests.
3.3 Report Provide a report detailing the field investigation, in-situ testing results and laboratory testing results, and to provide geotechnical design parameters. The content of the report include: 1) Recommendation of the appropriate types of foundation support required for each structure contemplated (i.e. spread footings, piles, caissons, compacted fill, etc.); 2) The bearing capacity for the service limit state (SLS) and ultimate limit state (ULS) of the substrata at stated elevations, and the anticipated uniform and differential settlements; 3) Advice if weight of footing and soil above footing should be included when calculating footing bearing pressure in order to check against allowable bearing pressure; 4) If deep foundations are to be considered, the types of deep foundations, the vertical and lateral SLS and ULS load capacities for piles and/or caissons, and assessment of obstructions likely to be encountered during the installation of piles and/or caissons, and inspection and testing requirements during the installation; 5) Minimum depths at which foundations can be founded and minimum depth of soil required above bearing elevations, if this is a design requirement for bearing capacity; 6) Determination of the safe-bearing capacity and horizontal sliding friction factor for spread footing design; M2112-2840010 Page 2
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7) Determination of allowable pile load, pile spacing, lateral bearing value, and reduction values (if applicable) for individual pile values when in a group; 8) Unit density of soil and coefficients of active and passive earth pressures for design of members resisting lateral loads and coefficient of friction for footings on soil; 9) Determination of angle of friction, equivalent fluid pressure, and allowable passive soil pressure for wall design; 10) Settlement analysis for typical structural and equipment loads supported by spread footings, for estimated allowable settlement of 6 mm and 12 mm; 11) Backfilling requirements including types of imported fill and degree of compaction, and engineered fill requirements if footings are recommended to bear on compacted fill; 12) Recommendations for pipe bedding and backfill, trench slope stability, soils envelope under building footings which cannot be disturbed, and permeability rates of the soils; 13) Determination of slide potential of natural and fill slopes where affected by adjacent structural and fill slopes and recommendations for cut and fill areas; 14) Determination of any special construction techniques such as preloading or precautions which may be required by unusual subsoil of ground water conditions; 15) Determination of any special permanent perimeter and under-floor drainage requirements, including estimate of the amount of ground water to be pumped; 16) Determination of subgrade modulus and modulus of compression of the soil and recommendation for special foundation preparation, if required, to support dynamic loads; 17) Determination of the frost penetration depth and required depths for foundation on natural soil, foundation on fill and buried pipes and conduits; 18) Determination of any shrinkage or swelling of soils which could affect design of foundations of floor slabs; 19) In the event that removal of existing soils and replacement with borrow materials is required; recommendations for local source and quality restraints for borrow backfill and recommendations for compaction requirements of fill; 20) An assessment of any corrosive properties of soils which may affect construction (e.g. soil resistivity, water soluble sulfate content, water soluble chloride content, pH value, and total acidity); 21) Mitigating corrosive soil and ground water effects, if any; 22) CBR values for rail line design; 23) Suitability of the soil on site to support slabs-on-grade and paved areas as well as the coefficient of subgrade reaction for design of slabs-on-grade and concrete pavements; 24) Suitability of the soil on site for use as compacted fill under slabs-on-grade and paved areas, or for use as backfill to exterior walls and the method of compaction; 25) Allowable bond stress for the design of permanent, prestressed soil and/or rock anchors; 26) Site classification for seismic site response; M2112-2840010 Page 3
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27) Recommendations for temporary shoring of excavations, including design requirements for both raker and tie-back systems; 28) Identification of any unusual problems likely to arise during excavation or during construction of foundations and site services; 29) Recommended methods of dewatering during construction if a high water table is encountered; 30) Any flooding requirements; 31) The report shall be certified, signed and stamped by a professional engineer licensed in the province of Saskatchewan.
4.0 Methodology 4.1 Field Investigations 4.1.1
Geotechnical Boreholes
Ground Breakers Drilling Ltd. (GB) of Carnduff, SK was contracted for the geotechnical drilling and piezometer installations. GB mobilized to Saskatoon on 16 February 2010 and utilized a truck-mounted mobile B-61 continuous flight auger drill rig for the investigation. All 8 boreholes for foundation analysis were completed by 27 April 2010. Drilling was stopped on two occasions during the work period due to soft ground condition after snow melt. The borehole details are summarized in Table 4.1 and the borehole locations are shown on the Figure A2 in Appendix A. The boreholes were decommissioned using cement-bentonite grout (96% cement to 4% bentonite ratio (by weight)) to reduce long-term environmental liability associated with the boreholes. Disturbed auger cuttings, split-spoons, and Shelby Tube samples were obtained during the drilling of boreholes and the soils were logged on-site for field descriptions of the encountered lithology. All collected soil samples were bagged and transported to MDH soil testing laboratory in Saskatoon every day after drilling. Field testing included Standard Penetration Testing (SPT) and pocket penetrometers (pocket pen) testing. SPT testing was conducted at approximately 1.5 m (5 ft) intervals. The sampling depths and the results of field tests are also annotated on the borehole logs presented in Appendix B. The Terms, Symbols and Abbreviations used on the borehole logs are also appended. Detailed descriptions of the drilling activities are discussed in the following sections. The termination depths of the boreholes ranged from 18.3 m to 29.0 m (60 ft to 95 ft), the shallower depths were due to the presence of sand layer (Dalmeny aquifer) at approximately 15 m to 20 m (49 ft to 66 ft) below ground.
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4.1.2
June 2010
Geotechnical Test Pits
Nemanishen Contracting Ltd. (NCL) was contracted for the excavation and backfill of the test pits. NCL mobilized a John Deere 410E backhoe for this project. Sixteen (16) test pits were excavated within the project site area:
Two (2) of them within the plant site footprint; Seven (7) of them along the rail line alignment; and, The remainder in various areas around the site for other project components.
All 16 test pits were completed between 03 May 2010 and 07 May 2010. The test pit details are summarized in Table 4.1 and the test pit locations are shown on Figure A2 in Appendix A. The test pit depths were all approximately 3.0 m (10 ft). Pocket pen tests were carried out in the field at regular intervals and soils were logged on-site for field descriptions. The test pit logs are presented in Appendix B. The Terms, Symbols and Abbreviations used on the borehole logs are also appended. Soil samples were collected every 0.5 m (1.5 ft) vertical interval, placed in polyethylene bags and transported to the MDH soil laboratory in Saskatoon after excavation and stored in humidity controlled room. The test pits were backfilled with the excavated material and the grounds were re-graded by the backhoe excavator.
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Table 4.1 – Borehole and test pit summary. Borehole / Borehole / Testpit Depth Testpit Designation (m) (ft)
Date Installation Drilled / Type Excavated
Coordinates (NAD 83) Northing (m)
Easting (m)
Piezometer depth (meter Top of Piezometer below Ground piezometer tip ground) cap Elevation (masl)
Boreholes M2112-06
19.8
65.0
19-Feb-2010 Piezometer
5802483.01
370350.72
521.86
522.79
513.68
8.18
M2112-07
29.0
95.0
4-Mar-2010
M2112-08
21.3
70.0
5-Mar-2010
-
5802468.29
370228.35
522.31
-
-
-
-
5802382.34
370227.96
521.86
-
-
-
M2112-09
18.3
60.0
M2112-10
18.9
62.0
5-Mar-2010
-
5802380.04
370349.83
523.03
-
-
-
6-Mar-2010
-
5802378.15
370466.85
522.22
-
-
M2112-11
18.9
-
62.0
6-Mar-2010
-
5802463.73
370469.03
522.75
-
-
-
M2112-17 M2112-18
18.3
60.0
27-Apr-2010
-
5802512.67
370487.48
522.82
-
-
-
18.3
60.0
27-Apr-2010
-
5802560.41
370241.34
522.01
-
-
-
Test Pits M2112-22
3.1
10.0
29-Apr-2010
-
5803174.21
370900.16
523.65
-
-
-
M2112-23
3.2
10.5
29-Apr-2010
-
5803427.80
370700.80
522.64
-
-
-
M2112-24
3.2
10.5
3-May-2010
-
5802431.25
370399.95
522.63
-
-
-
M2112-25
3.1
10.0
3-May-2010
-
5802424.27
370281.41
522.53
-
-
-
M2112-26
3.1
10.0
3-May-2010
-
5802406.73
370187.15
522.22
-
-
-
M2112-27
3.1
10.0
3-May-2010
-
5802346.30
370030.94
522.34
-
-
-
M2112-28
3.1
10.0
3-May-2010
-
5802458.86
369982.60
522.68
-
-
-
M2112-29
3.2
10.5
3-May-2010
-
5802540.06
370100.70
521.94
-
-
-
M2112-30
3.2
10.5
3-May-2010
-
5802512.55
370315.12
522.59
-
-
-
M2112-31
3.5
11.5
3-May-2010
-
5802564.35
370334.01
522.40
-
-
-
M2112-32
3.4
11.0
3-May-2010
-
5802697.60
370358.50
522.83
-
-
-
M2112-33
3.4
11.0
7-May-2010
-
5802179.49
370895.38
521.94
-
-
-
M2112-34
3.4
11.0
7-May-2010
-
5802309.56
370772.69
521.99
-
-
-
M2112-35
3.5
11.5
7-May-2010
-
5802539.27
370891.68
522.51
-
-
-
M2112-36
4.0
13.0
7-May-2010
-
5802839.57
370705.07
522.49
-
-
-
M2112-37
3.2
10.5
7-May-2010
-
5802434.60
370642.42
522.38
-
-
-
4.1.3
Standpipe Piezometer Installation and Shallow Groundwater Regime
One (1) Casagrande style standpipe piezometer was installed to a depth of 8.5 m (27.8 ft) below ground level in borehole M2112-06 to collect shallow groundwater elevations. The piezometer completion details are provided in Appendix B. The standpipe piezometer consists of a 50 mm diameter schedule 40 PVC pipe with 1.5 m (5 ft) length of horizontally slotted screen at the bottom. Water levels in the piezometer were measured between March 2010 and May 2010 and the data is presented in Table 4.2. The highest measured groundwater level was at 5.89 m (19.32 ft) below ground. However, the Surficial Stratified Deposits near ground surface are expected to be saturated during wet seasons.
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It is anticipated that the groundwater levels will vary from the observed elevations due to seasonal fluctuation and in response to wet or dry weather conditions. Changes in groundwater levels will also be observed in response to changes of surface drainage patterns. Table 4.2 – Groundwater monitoring records. Ground Piezometer Water Depth (m below ground) Groundwater Elevation (masl) Piezometer Elevation Top of Casing 7-Apr-2010 20-Apr-2010 6-May-2010 20-May-2010 7-Apr-2010 20-Apr-2010 6-May-2010 20-May-2010 (masl) (masl)
M2112-06
521.86
522.79
7.24
7.31
7.35
5.89
514.62
514.55
514.51
515.97
Note: The underlined values are the highest measured groundwater level at the site.
4.2 Laboratory Testing 4.2.1
Geotechnical and Index Soil Properties
The laboratory testing for the samples from boreholes included grain size distributions, water contents, unconfined compression tests, group index, Atterberg limits, specific gravity, direct shear tests and high load consolidation tests. Samples were selected for laboratory testing to best represent the stratigraphic layers encountered during the drilling to produce an understanding of the soil conditions and soil properties within the project area. Table D1 in Appendix D provides a summary of the laboratory testing results. Detailed laboratory testing results are also provided in Appendix D. All soils testing, with the exception of the detailed salinity testing, was conducted by the MDH soils laboratory in Saskatoon, SK. 4.2.2
Unconfined Compression Test
Unconfined compressive strength testing was conducted on undisturbed samples from the Shelby tubes obtained during the drilling investigation, where sample was suitable. A summary of the test results for the unconfined compressive strengths are shown in Table 4.3.
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Table 4.3 – Summary of unconfined compression strength results. Borehole Number M2112-08 M2112-06 M2112-11 M2112-10 M2112-09 M2112-08 M2112-06 M2112-07 M2112-06 M2112-08 M2112-07
4.2.3
Sample Number CTS-60 CTS-06 CTS-141 CTS-115 CTS-92 CTS-68 CTS-13 CTS-39 CTS-21 CTS-82 CTS-54
Stratigraphic Layer Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till Oxidized Silt Till
Sample Depth (ft) (m) 9.0 2.7 13.0 4.0 16.5 5.0 19.0 5.8 21.5 6.6 24.0 7.3 25.5 7.8 26.5 8.1 46.5 14.2 56.5 17.2 61.5 18.7
Unconfined Compressive Strengths, qu (kPa) 123 282 286 664 680 518 321 407 730 513 421
Oedometer / Consolidation Test
Oedometer Testing was performed to determine one-dimensional consolidation or swelling using incremental loading (ASTM D2435). Three (3) samples obtained from various depths were selected for consolidation tests at the MDH soil laboratory. A summary of the test results is shown in Table 4.4. The detailed results for the Oedometer testing are provided in Appendix D. The Casagrande semilog method (1936) was used for evaluation of the preconsolidation pressure, po. The test results for sample CTS-82 were disregarded due to the unreasonably low pre-consolidation pressure obtained, possibly as a result of soil disturbance during sampling.
(ft)
(m)
Compression Index, Cc
Rebound Index, Cr
Swelling Pressure (kPa)
Stratigraphic Layer
Over Consolidation Ratio, OCR
Sample Number
Preconsolidation Pressure, po
Borehole Number
Initial Void Ratio, eo
Table 4.4 – Summary of consolidation test results.
7.5 - 9.0
2.3 - 2.7
0.49
100
1.9
0.12
0.03
11.9
6.9 - 7.3
0.32
275
1.7
0.09
0.03
77.4
0.34
-
-
-
-
-
Sample Depth
M2112-08
CTS-60 Oxidized Silt Till
M2112-08
CTS-68 Oxidized Silt Till 22.5 - 24.0
M2112-08
CTS-82 Oxidized Silt Till 55.0 - 56.5 16.8 - 17.2
4.2.4
Direct Shear Test
The Direct Shear testing (ASTM D3080-90) was conducted to determine the drained shear strength of selected in-situ soil samples. Tests on three (3) samples recovered from various depths were completed at the MDH soil laboratory. The test report graphical plots are presented in Appendix D and the test results are summarized in Table 4.5.
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Table 4.5 – Summary of direct shear test results. Residual Angle of Shear Sample Sample Depth (ft) Depth (m) Apparent Resistance Cohesion, of Soil, ' (degree) c' (kPa)
Peak Angle of Shear Apparent Resistance Cohesion, of Soil, ' (degree) c' (kPa)
Borehole Number
Sample Number
Stratigraphic Layer
M2112-08
CTS-60
Oxidized Silt Till
9.0
2.7
5.0
28.0
14.0
30.0
M2112-09 M2112-10
CTS-92 CTS-120
Oxidized Silt Till Oxidized Silt Till
21.5 31.5
6.6 9.6
5.0 2.0
29.0 29.0
13.0 25.0
32.0 30.0
4.3 Undrained Shear Strength, su The average undrained shear strengths obtained from field pocket penetrometers tests and laboratory unconfined compression tests at various depths are summarized in Table 4.6. No laboratory undrained shear strength tests were performed on samples from the 30 ft to 40 ft depth interval because of insufficient sample size and/or poor sample condition. Table 4.6 – Average undrained shear strengths of soil at various depths.
Sample Depth from
Sample Depth to
Average Undrained Average Undrained Average Undrained Shear Strength from Shear Strength from Shear Strength Pocket Pen Lab Tests (Field & Lab Tests) su su su
(ft)
(m)
(ft)
(m)
kPa
kPa
kPa
0
0.0
10
3.0
87
62
74
10
3.0
20
6.1
136
205
171
20
6.1
30
9.1
197
241
219
30
9.1
40
12.2
190
-
190
40
12.2
50
15.2
157
365
261
50
15.2
60
18.3
161
257
209
60
18.3
70
21.3
110
211
160
149
223
184
Overall Average
4.4 California Bearing Ratio, CBR California Bearing Ratios (CBRs) were calculated for the rail line alignment from Group Index test results based on the Saskatchewan Ministry of Highways and Infrastructure Surfacing M2112-2840010 Page 9
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Manual (SM 940). The (soaked) CBR results are summarized in Table 4.7. Detailed laboratory testing results are provided in Appendix D. Sample CTS-543 from test pit M2112-34 was a non-plastic sand and therefore no Group Index or CBR was obtained for this sample. Table 4.7 – Summary of calculated CBRs results. Test Pit Number M2112-24 M2112-25 M2112-26 M2112-27 M2112-33 M2112-34 M2112-37
Sample CTS-501 CTS-506 CTS-511 CTS-515 CTS-539 CTS-543 CTS-556
Sample Depth (ft) (m) 3.5 1.1 5.0 1.5 4.0 1.2 2.0 0.6 3.5 1.1 2.0 0.6 3.5 1.1
Group Index
CBR
20.0 11.9 20.0 6.3 17.4 20.0
2.5 4.6 2.5 6.7 3.1 2.5
4.5 Chemical Laboratory Investigation Six (6) soil samples were submitted to ALS Laboratory in Saskatoon for analysis of soil chemistry. Detailed salinity testing (saturation paste method) was conducted to determine Cl-, K, Mg, Na, SO4, electrical conductivity (EC) and pH for the soils in the project area. A summary of the chemical constituents and Electrical Conductivity (EC) for the pore water in each of the soil samples tested for the study are is presented in Table 4.8. The original ALS Laboratory data sheets are provided in Appendix D. The laboratory detailed salinity test results show that the soil at the site has moderate to very severe degree of exposure in sulphate (SO4) content (CSA A23.1-04). Sulphates are naturally occurring in Saskatchewan tills to differing degrees. The average value of pore water sulphate contents tested was 3,522 mg/L. Chloride (Cl-) exposure is also known to lead to corrosion in reinforced concrete structures. The average chloride content in the samples tested was 49 mg/L. A designer competent in concrete mix design should complete the concrete mix design specifications, but it is anticipated that sulphate resistant cement may be used, as this is common practice in Saskatchewan.
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Table 4.8 – Summary of soil porewater chemistry results. M2112-07 L872023-1 CTS - 33 14' mg/L 11.4 Chloride (Cl) mg/L 531 Calcium (Ca) mg/L 30.5 Potassium (K) mg/L 163 Magnesium (Mg) mg/L 38.7 Sodium (Na) SAR 0.38 SAR mg/L 1820 Sulphate (SO4) % 37.1 % Saturation pH 7.48 pH in Saturated Paste dS m-1 2.80 Conductivity Sat. Paste Detailed Salinity (Corrected for Pore Water) Parameter
Units
Natural Moisture Content Corrected Salinity values Chloride (Cl) Calcium (Ca) Potassium (K) Magnesium (Mg) Sodium (Na) Sulphate (SO4) Class of Sulphate exposure
% mg/L mg/L mg/L mg/L mg/L mg/L
Notes:
M2112-06 L872023-2 CTS - 02 3' 14.3 45.1 12.3 19.3 10.6 0.33 70.0 35.8 7.90 0.43
M2112-09 L872023-3 CTS - 84 3' 23.7 17.7 10.4 53.9 53.6 1.43 78.6 37.8 8.48 0.70
M2112-08 L872023-4 CTS - 59 7' 7.0 29.4 8.4 20.2 14.8 0.51 24.9 77.7 7.84 0.36
M2112-11 L872023-5 CTS - 140 14' 28.9 452 32 738 289 1.95 4240 39.1 7.81 5.70
M2112-10 L872023-6 CTS - 112 10' - 11.5' 5.0 56.7 8.9 24.7 12.0 0.34 82.1 72.0 7.67 0.48
12.93
12.49
9.62
33.41
10.92
36.22
33 1524 88 468 111 5222 S-2 (severe)
41 129 35 55 30 201 S-3 (moderate)
93 70 41 212 211 309 S-3 (moderate)
16 68 20 47 34 58 S-3 (moderate)
103 1618 115 2642 1035 15182 S-1 (very severe)
10 113 18 49 24 163 S-3 (moderate)
1. Chemical contituent concentrations determined using the saturation paste method. Deionized w ater is added to the soil until the soil is saturated. The paste is allow ed to stand overnight or a minimum of four hours. After equilibration, an extract is obtained by vacuum filtration. Chloride in the extract is determined colorimetrically at 660nm by complexation w ith mercury (II) thiocynate. Individual cations are derermined by ICP-OES. pH of the soil paste is measured using a pH meter. Conductivity of the extract is measured by a conductivity meter. 2. Values provided at bottom of table (in green) are estimates of pore w aterconcentration, determined by: [(%Water Saturation / %Water natural content)*(Csat.paste)] 3. Class of Sulphate exposure refer to Table 3 of CSA A23.1-04, Concrete materials and methods of concrete construction.
5.0 Subsurface Condition 5.1 Local Geology The general subsurface stratigraphy within the project site consists of:
0.1 m (0.3 ft) to 0.5 m (1.5 ft) of topsoil, overlying; 0.1 m (0.3 ft) to 3.2 m (10.5 ft) of Surficial Stratified Deposits (SSD), overlying; Approximately 1.0 m (3.3 ft) of Battleford Formation, overlying; 12.0 m (39.4 ft) to 17.0 m (55.8 ft) of Upper Floral Formation, overlying; Intra-till sand (Upper Floral Aquifer/ Dalmeny Aquifer)
All of the boreholes were terminated within the Upper Floral Formation of the Saskatoon Group due to the limitation of drilling depths. The glacial till soil encountered in this area is
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generally heterogeneous fine grained soil with relatively low permeability which can also be described as poorly drained soil. Saskatoon Group The Saskatoon Group was first proposed by Christiansen (1968) as the portion of drift lying between the Sutherland Group and the ground surface. The Saskatoon Group is subdivided into the Floral Formation, the Battleford Formation, and the SSD. The Floral Formation consists of a Lower and Upper unit by distinct glaciations. These units are often separated by the Riddell Member of the Floral Formation. The Riddell Member is a stratified interglacial deposit of Sangamon age (Skwarawoolf, 1981) and forms a significant aquifer in Saskatchewan which is informally called the Upper Floral Aquifer. This is called the Dalmeny Aquifer in the project area. This unit is continuous across the project area and was encountered in all the boreholes. All the boreholes drilled as part of the investigation were terminated in this stratigraphic unit. 5.1.1
The Surficial Stratified Deposits (SSD)
Surficial Stratified Deposits (SSD) of the Saskatoon Group were encountered in various thickness around in the vicinity of the proposed mine site. The SSD are mainly derived from weathered or re-worked Battleford Formation till and both water and wind derived sand, silt and clay deposits. The soils encountered in this stratum during this investigation were layered sand, silt and clay. 5.1.2
The Battleford Formation
The Battleford Formation is located between the Floral Formation and Surficial Stratified Deposits. This layer of soil was described as sandy silt till consisted some clay and trace amount of gravel, brown in color, oxidized, soft to firm in consistency, low plasticity, moist, patchy oxide (iron) staining was prevalent throughout the unit. The stratigraphic contact with the underlying Floral Formation was primarily based on the presence of intact fractures within the Floral Formation, color change, and consistency variation (soil hardness increases in Floral Formation due to the highly overconsolidated nature of the Floral Formation till compared to that of the Battleford Formation till). 5.1.3
The Floral Formation
The Upper Floral Formation till encountered was described as sandy silt till consisted some clay and trace amount of gravel, brown in color in the shallower depth (transition from Battleford Formation above) overlying grey in color with oxide stained fractures in deeper depth, oxidized, stiff to hard in consistency, low plasticity and moist.
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Upper Floral Aquifer (Dalmeny Aquifer)
Upper Floral Aquifer was encountered at depths between 15.2 m (50 ft) (M2112-11) to 20.4 m (67 ft) (M2112-08) and all the boreholes were terminated within this aquifer. This sand layer was described as fine to coarse sand, trace silt, trace clay, brown or brown to grey in color, very dense in compactness and wet in moisture condition.
6.0 Ground Resistivity Test Ground resistivity testing was performed as a part of the geotechnical investigations at the site. The approximate test locations are shown on Figure A2 in Appendix A. The ground resistivity test was performed on 07 May 2010. Soil resistivity measurements were taken with nine (9) incremental probe distances in accordance with the Equally Spaced (Wenner Arrangement) Four-Point Method in IEEE Std 81 – 1983. The test configuration and ground resistivity results are presented in Appendix C.
7.0 Geotechnical Recommendations 7.1 General The stratigraphy was found to be relatively consistent across all the boreholes, where sandy silt till is overlain by a SSD layer. All eight (8) boreholes were terminated in a wet sand layer (Upper Floral Aquifer). The bottom of this sand layer was not encountered in the geotechnical boreholes as the deepest hole was drilled to 29 m (95 ft), which is beyond the typical pile depth. The following subsections provided general guidelines and recommendations for site grading and subgrade preparation, site drainage, and foundation recommendations. Foundation recommendations and calculations found in this report are based upon the methods presented in the Canadian Foundation Engineering Manual (CGS, 2006) (CFEM), unless otherwise indicated. Detailed descriptions of the soils encountered are presented on the borehole logs in Appendix B.
7.2 General Site Grading, Clearing, and Site Preparation 7.2.1
General Site Grading and Clearing
As a minimum requirement, all surface vegetation, organics (topsoil), trash, debris, and other deleterious materials should be cleared and removed from the footprint of planned structures. Topsoil present at the surface should be stripped and removed from all areas M2112-2840010 Page 13
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requiring subgrade support. Areas requiring subgrade support include building footprints, concrete pads, and roadways. The plant site area is generally flat in nature. The ground elevation difference revealed from the topographical survey plan (Figure A3, Appendix A) is within 1.75 m (5.7 ft). The required site grading is considered to be minimal. The topsoil should be removed during grading. Topsoil may be stockpiled and re-used for non-structural areas only, such as landscaping. Reusing this material as backfill soil for subgrade support is not recommended. The topsoil thickness encountered in the boreholes and test pit was approximately 0.1 m (0.3 ft) to 0.5 m (1.5 ft) in general and the expected maximum thickness can be locally up to 0.6 m (2.0 ft) or more. For cost estimation and general site planning, the assumption of 0.3 m (1 ft) of top soil will be appropriate for all locations around the future plant site buildings. 7.2.2
Permanent Cut Slopes
A slope angle of 2.5H:1V (21.8°) to 3H:1V(18.4°) for the permanent cut slope may generally be deemed to be appropriate for general planning and cost estimation. It is recommended that slope stability analysis be conducted to verify stability of permanent slopes with height larger than 3 m (9.8 ft). The permanent cut slope angle should be designed by a professional engineer with geotechnical experience in slope stability design to ensure a sufficient factor of safety is achieved. The construction process should be supervised by qualified personnel to ensure the workmanship and the soil encountered has not significantly deviated from the design soil type. The stability of the permanent cut slopes is dependent on the soil type, groundwater conditions and potential loading conditions at the crest. The factor of safety requirement may vary depending on the type of infrastructure located within the vicinity of slope. A higher factor of safety may be required if the risk of life or risk of economy loss is higher in the case of slope failure and vice versa. The design engineer should make the appropriate judgement. 7.2.3
Fill Slopes
The permanent fill slope angle can generally be varied from 2.5H:1V (21.8°) to 3H:1V (18.4°) or flatter depending on the property of fill material, facility at crest and the design groundwater condition. It is recommended that a slope stability analysis be conducted to verify stability of permanent slope with height larger than 3 m (9.8 ft). The permanent fill slope angle should be designed by a professional engineer with geotechnical experience in slope design to ensure a sufficient factor of safety is achieved. The construction process should be supervised by qualified personnel to ensure the quality workmanship.
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The stability of the slopes is dependent on the soil type, groundwater conditions and potential loading conditions at the crest. The factor of safety requirement may vary depending on the type of infrastructure located within the vicinity of slope. A higher factor of safety may be required if the risk of life or risk of economy loss is higher in the case of slope failure and vice versa. The design engineer should make the appropriate judgement.
7.3 Temporary Excavation and Dewatering 7.3.1
Temporary Cut Slope for Excavation
If workers entering the excavated trench, the temporary slope angle of excavation shall follow the recommendation stated in the Occupation Health and Safety, 1996 (OHS). The soil at shallow depth in this site may be classified as type 3 and type 4 at different locations; the maximum slope angle for type 3 soil and type 4 soil shall be 1H:1V (45°) and 3H:1V (18.4°), respectively. A copy of the relevant section for excavation safety in OHS is attached as Appendix E. Variability in surface soils exists, and it is recommended that a qualified person conduct an inspection of any excavations prior to workers entering the excavated area. The excavation slopes should be checked regularly for signs of spalling, cracking, tension crack at crest, etc., particularly after periods of rain. Local flattening of the excavation slopes may be required where instabilities of the cut slopes are observed. 7.3.2
Utility Trench Excavation
Utility trenches with steeper cut slopes may be allowed if no workers will enter the trench; sufficient measures should be taken to protect the stability of adjacent structures and human safety. The utility trench slope angle should follow the recommendations in attached OHS guidelines (Appendix E) if workers will be entering the trench to ensure a safe working environment. Temporary soil protective measures designed by a professional engineer may be needed. Variability exists in the surface soils, and it is recommended that a qualified person conduct an inspection of excavations prior to workers entering the excavated area. 7.3.3
Foundation Excavations
Foundation excavations that are left open for extended periods may collect groundwater seepage, which can likely be handled by pumps. Any surface water or groundwater infiltration into the foundation excavation should be diverted away from the foundation base to avoid softening. In warm, dry weather, care should also be taken to prevent the soil at the base of the excavation from becoming dry and cracked. It is good practice to protect the base of the footing excavation with a concrete mud slab immediately after footing excavation, particularly if wet weather is anticipated.
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Where buried services are to be located near building foundations, the bottom of footings should be established below an imaginary line projected at 1.0H:1.0V (45°) upward from the invert level of the service line to reduce the risk of undermining such footings. 7.3.4
Soil and Material Stockpiling Near Excavation
As stated in OHS 260(1), equipment, spoil pile, rocks and construction materials are to be kept at least one metre from the edge of an excavation or trench. The stockpiling distance from the crest of the excavation will be preferably equal to or greater than the depth of excavation, especially when the trench will remain open for a relatively longer period. 7.3.5
Temporary Dewatering
In most situations, a peripheral trench with one or two low points for a standard sump pump may be sufficient for dewatering a shallow excavation; close monitoring on the groundwater ingress into the trench by qualified personnel is recommended. Other dewatering methods may be required if this method proves to be insufficient. It is difficult to estimate the amount of water that will be encountered, as surficial soils are stratified and variable across the site. The surficial stratified soils may be water bearing during spring or following precipitation events. As a result, it may be beneficial to strip this material away from excavation footprints to reduce water ingress. Surface drainage should be directed away from the crest of any excavation.
7.4 Site Surface Drainage Excess water should be drained from the site as quickly as possible both during and after construction. Roof and other drains should discharge well clear of any buildings and equipment. Initial grading operations should also be focused on providing surface drainage, such that precipitation and surface run-off is directed off the construction area. Within 2 m (6.6 ft) of the building perimeter, hard surfacing (asphalt or concrete) should be graded to slope away from buildings at a gradient of at least 2 percent. Landscaped areas should be graded at least 5 percent to promote run-off from buildings.
7.5 Subgrade Preparation 7.5.1
General
The following provides recommendations for general soil subgrade preparation in order to produce a uniform bearing condition for the planned structures. Following stripping of topsoil and excavation to design subgrade elevation (if required), the exposed subgrade should be inspected by qualified geotechnical personnel to verify the removal of unsuitable materials and to provide additional recommendations, as appropriate. Unsuitable materials include topsoil, organic matter, vegetation, oversized material with particle sizes larger than 75 mm,
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and other deleterious materials. The lateral extent of all excavations and removals should be at least 1.5 m (5 ft) from beyond the edge of structures. As a minimum, all exposed soil subgrades should be scarified to a minimum depth of 200 mm (8 inch), moisture conditioned (wetted or dried) to within optimum moisture content, and compacted in accordance with the recommendations outlined in Section 7.6. Specific recommendations for subgrade preparation for the various project components are provided in the following sections. 7.5.2
Proof Rolling
To verify that competent and uniform soil subgrade support conditions have been achieved, proof-rolling of the subgrade should be performed by two passes of a dual-wheel truck (or comparable equipment) with an 80 kN single axle load. Soils which display rutting or appreciable deflections upon proof-rolling should be over-excavated to expose the underlying more competent soil and replaced with suitable engineered fill compacted in accordance with the recommendations outlined in Section 7.6. If yielding or pumping conditions are encountered in subgrade areas, they may be stabilized by placing a layer of geogrid (Tensar BX 1200 or approved equivalent) directly on the bottom of the subgrade and backfilled with well graded 25 mm minus gravel compacted to at least 95 percent of the Standard Proctor Maximum Dry Density (SPMDD). Fill placement procedures should follow the recommendations provided in Section 7.6. Loose or soft areas should be identified during the initial site grading phase and addressed during construction. All finished subgrade should be protected from construction traffic and erosion as soon as possible. 7.5.3
Roadways
For subgrade support of the roadway, a uniformly smooth subgrade surface should be prepared, containing no ruts, pot holes, loose soils, or any imperfections that can retain water on the surface. Isolated pockets of frost susceptible material and organic topsoil should be removed and replaced with similar material adjoining the excavation to allow for uniform performance. As a minimum, the soils in all areas supporting vehicle traffic should be excavated to provide a minimum 0.3 m (1.0 ft) sub-cut below design subgrade elevations and re-compacted to provide a uniform bearing condition. The following soil subgrade recommendations should be followed, depending on whether the design soil subgrade is above or below the existing grade. The prepared subgrade should be crowned or crosssloped to facilitate the flow of surface water off the roadway. A minimum of 3 percent crossslope is recommended. As a minimum, all road subgrades should be designed in accordance with the standard specifications set forth by Saskatchewan Ministry of Highways and Infrastructure (SMHI).
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Fill Sections If the exposed subgrade surface is more than 0.3 m (1.0 ft) below the design subgrade elevation, the subgrade should only be prepared by scarifying to a minimum depth of 200 mm (8 inch), moisture conditioned (wetted or dried) to within ± 2 percent of optimum moisture content, and compacted to 98 percent of the Standard Proctor Maximum Dry Density (SPMDD). If the exposed subgrade surface is less than 0.3 m (1.0 ft) below the design subgrade elevation, the subgrade should be over-excavated to a minimum depth of 0.3 m (1.0 ft) below the design subgrade surface. The lateral extent of over-excavation should be at least 1.5 m (5 ft), or equal to the depth of over-excavation, whichever is greater. The exposed subgrade should then be scarified and compacted as outlined above. All fill soils placed to raise the subgrade elevation to design grade should be placed in loose lifts, moisture conditioned, and compacted as outlined above. Excavation Sections If the design subgrade elevation requires excavation, the subgrade should be overexcavated to a minimum depth of 0.3 m (1.0 ft) below the design subgrade surface. The lateral extent of over-excavation should be at least 1.5 m (5 ft), or equal to the depth of overexcavation, whichever is greater. The exposed soil subgrade should then be scarified and compacted as outlined above. Subgrade preparation should not be performed on very soft, loose or wet subgrade as construction equipment may further weaken the subgrade. Subsequent to scarification and compaction, the prepared subgrade should be proof rolled as discussed in Section 7.5.1 to create a uniform bearing condition and firm even surface. Recommendations to stabilize saturated, yielding or pumping subgrade conditions, should they be encountered, were also provided in Section 7.5.2. If any problems are encountered during the subgrade preparation, or if the site conditions deviate from those indicated by the boreholes, a qualified geotechnical personnel should be notified to provide additional recommendations.
7.6 Fill Placement and Compaction 7.6.1
Fill Materials
Excavations at the site between 0.0 metres below ground surface (mBGS) to 1.5 mBGS (0 ftBGS to 5 ftBGS) will generally consist of sand (SM), clay (CH) or sandy silt till (CL). The sand, clay and silt till were generally suitable for use as general fill materials provided that the soils are acceptably moisture conditioned (wetted or dried), free of appreciable amounts of contaminations, deleterious and/or organic materials, and free of particle sizes over 75 mm in diameter. M2112-2840010 Page 18
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If imported soils are selected for use as fill materials, the preferred soils are granular consisting of relatively clean, well graded, sand or mixture of sand and gravel with a maximum particle diameter of 75 mm. According to the local contractor, there is a granular material borrow-pit located 20 km to the west of Langham, but the soil will need to be tested prior to use. Prior to placement of fill material, representative bulk samples (about 25 kg) should be taken of the proposed fill soils and laboratory tests should be conducted to determine Atterberg limits, natural moisture content, grain size-distribution, and moisture-density relationships for compaction. These test results will be necessary for the proper control of construction for new engineered fill. Fill soils should not be placed in a frozen state, or placed on a frozen subgrade. All lumps of materials should be broken down during placement. Prior to placing any fill, the exposed surface soils should be observed by qualified geotechnical personnel to evaluate the removal of unsuitable materials, and to provide additional geotechnical recommendations, as appropriate. 7.6.2
General/Common Fill
The in-situ, sandy SSD, clay and silt till are likely suitable for general fill material but are not suitable for structural fill. As indicated from the soils encountered in the eight boreholes in this investigation, the in-situ silt till can be encountered anywhere from near the ground surface to 3.4 m (11 ft) below ground. This approximate depth is only for cost estimation and general development planning, and the base of the organic layer (topsoil) may be deeper near wetland and shallower in the other locations. Materials excavated at the proposed ponds within the site may be used as general fill for construction. General/common fill materials should be placed in loose lifts of 150 mm (6 inch) in thickness, be moisture conditioned (wetted or dried) to within ± 2 percent of optimum moisture content, and compacted to and 98% of Standard Proctor Maximum Dry Density (SPMDD) tested in accordance with ASTM Method D 698. 7.6.3
Structural fill
Structural fill should be free draining granular material that conforms to the gradation of subbase material specified in Table 7.1, or other gradations specified by a geotechnical engineer or structural engineer. The results of the investigation showed no easily available sources of structural fill within the project site. There are a few privately owned gravel pits within 100 km of the site, but a more detailed investigation of the available sources should be performed before construction.
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The structural fill should extend laterally 1 m or equal to the full depth of fill (whichever is the greater) beyond the footprint of a grade-supported area. It is important that the fill soils be compacted uniformly across the footing foundation/ slab area in order to minimize the potential of subsequent differential vertical movements. Structural fill materials should be placed in loose lifts of 150 mm (6 inch) in thickness, be moisture conditioned (wetted or dried) to within ± 2 percent of optimum moisture content, and compacted to and 100% of Standard Proctor Maximum Dry Density (SPMDD) tested in accordance with ASTM Method D 698. 7.6.4
Road base
The well-graded granular sub-base and base materials should conform to the gradation shown in Table 7.1. Placement of the sub-base and base granular fill should not be conducted in freezing conditions. Both granular base fill material and granular sub-base material should be placed in loose lifts of 150 mm (6 inch) in thickness, be moisture conditioned (wetted or dried) to within ± 2 percent of optimum moisture content, and compacted to and 100% of Standard Proctor Maximum Dry Density (SPMDD) tested in accordance with ASTM Method D 698. 7.6.5
Underground utilities bedding
Bedding material varies for different utilities, and attention should be given to the specifications for the different utilities types. However, well-graded granular base material conforming to the sub-base gradation shown in Table 7.1 may be used as a free draining bedding material or surrounding material for water carrying utilities. Placement of the bedding material should not be conducted in freezing conditions. 7.6.6
Utilities trench backfill
Well-graded granular base material conforming to the sub-base gradation shown in Table 7.1 or another gradation approved by a geotechnical engineer may be used for utilities trench backfill in traffic areas and the general fill described in Section 7.6.2 can be used for utilities backfill in off-road areas.
7.7 Procedures to Mitigate Frost Action in Buried Utilities The native soil near ground surface consisting of silt and clay is considered to be moderately to highly frost susceptible. Buried utilities that are frost susceptible should have a minimum frost cover of 2.7 m (9.0 ft) if granular backfill (gravel and sand) is used. Utilities buried with less than the recommended soil cover should be protected with insulation to avoid frost effects that may cause damage to the utility pipes. Rigid insulation placed under areas subject to vehicular wheel loads should be provided with a minimum cover of 600 mm (2 ft) of compacted granular base and/or pavement. M2112-2840010 Page 20
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Table 7.1 – Base and sub-base gradation specifications. Percent Passing by Weight Sub-Base Base Coarse Type 31 Type 33 Type 6 100 100
Sieve Size 50 mm 31.5 mm 25 mm 22.4 mm 18 mm 16 mm 12.5 mm 9 mm 5 mm 2 mm 900 m 400 m m 160 m 71 Plasticity Index Fractured Face % Lightweight pieces %
75 - 90
100
65 - 83
75-100
40 - 69 26 - 47 17 - 32 12 - 22 7 - 14 6 - 11 0-7 Min 50 Max 5
50 - 75 32 - 52 20 - 35 15 - 25 8 - 15 6 - 11 0-6 Min 50 Max 5
0 - 80 0 - 45 0 - 20 0-6 0-6
Note: Adopted from SMHI's Standard Specification Manual.
7.8 Lateral Earth Pressure Coefficients The determination of lateral earth pressures will be required for the design of subsurface foundation walls, sumps, retaining walls, etc. Horizontal soil forces should be determined based on “at-rest” (Ko) earth pressure conditions where the horizontal stress is: h = Kov = KoH The recommended lateral earth pressure coefficients and unit weights are provide in Table 7.2. Table 7.2 – Lateral earth pressure coefficients and soil unit weights.
Soil Type
Ko
Ka
Total Unit Weight, (kN/m 3)
Compacted Granular Fill
0.45
0.29
22
Compacted Cohesive Fill
0.6
0.42
20
Native Silt Till
0.6
0.42
22
Where the parameters in Table 7.2 are used for estimating horizontal loads on walls backfilled with granular soil, the width of the granular section should be at least 3 m wide at
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the bottom of the wall and should be sloped upwards at no steeper than 1H:1V away from the wall. The shape of the lateral pressure distribution will depend on the degree of compaction achieved in the soil backfill against the wall. Where the backfill adjacent to the wall will be compacted to 95 percent of the Standard Proctor Maximum Dry Density (SPMDD) or greater, the design earth pressure should adopt a combined trapezoidal/triangular distribution as per Figure 7.1. The relationships to be used in calculating the lateral pressures are also given in Figure 7.1 and load of typical compactors are given in Table 7.3. Where subdrainage will not be provided, two cases should be considered in the calculation of the lateral pressures: 1) The case immediately following fill placement and compaction, where the groundwater level has not been re-established. In this case the total soil unit weights provided in Table 7.2 should be used. 2) The longer term case where the groundwater level is re-established. In this case buoyant soil unit weights (’ = – 9.8 kN/m3) should be used to calculate the horizontal stress below the depth of the groundwater level and a hydrostatic pressure component due to water pressure will need to be added. The greater of case 1) or 2) above should be used for design. In addition to earth pressure, lateral stresses generated by line, point or surcharge loads, from such as equipment and/or embankment fill, also require consideration in the design of retaining structures. MDH would be pleased to assist with the design of such cases upon request. To reduce the potential of lateral hydrostatic or frost forces developing due to accumulation of water, it is recommended that clean free-draining, non-frost susceptible granular soil with less than 5 percent particles by weight smaller than 0.08 mm in size, be used as backfill within a minimum 1 m wide zone behind retaining structures. A perforated drainage pipe enclosed in a geotextile sock should be installed along the bottom of the walls with positive drainage to a discharge point. The structural engineer may present other options to deal with the effects of lateral hydrostatic or frost forces acting upon structures. However, it may be noted that shallow groundwater conditions at some locations may prevent the use of some alternatives (i.e. void forms) in the frost zone. In areas that are not paved, the upper 600 mm of backfill should consist of inorganic clay fill, to reduce the potential of surface water infiltration behind the wall. The ground or pavement surface should be graded to promote positive drainage away from the wall.
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Zc Z d 'h
For Zc ≤ Z ≤ d, For Z > d,
'h
= soil unit weight K = Ko (see report text)
,
see also table Table 7.3 for typical compactor load Figure 7.1 – Horizontal pressure on walls induced by compaction effort. Table 7.3 – Typical compaction equipment data for estimating compaction-induced loads.
Single-drum walk-behind
Dead Weight of Roller (kN) 2.3
Centrigugal Force (kN) 8.3
Roller Width (mm) 560
Dual-drum walk-behind
1.6
10.1
560
20.9
Dual-drum walk-behind
12.1
8.8
760
27.5
Dual-drum walk-behind
9.2
19.8
750
38.7
Equipment Type
P (kN/m) 18.9
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7.9 Frost Penetration Depth The observed frozen ground depth during previous preliminary geotechnical drilling in February 2010 and March 2010 was approximately 1.8 m to 2.7 m (6 ft to 9 ft) below grade. The frost depths calculated by the modified Berggren equation given by CFEM are summarized in Table 7.4. Table 7.4 – Calculated frost penetration depth under various surface covers. Return Period (years) 10 25
Frost Penetration Depth (mBGS) (ftBGS) 2.5 8.3 2.7 9.0
7.10 Foundations 7.10.1 Shallow Foundations Boreholes M2112-06, M2112-07, M2112-11, M2112-17 and M2112-18 were drilled at the location of the proposed plant site. The soil below 2.7 mBGS (9.0 ft) was firm clay to very stiff sill till. The future shallow foundations are assumed to be founded on stiff to very stiff till. The firm clay shall be replaced with sub-base material specified in Table 7.1 and compacted in accordance with Section 7.6 of this report. If shallow foundations are selected by the foundation designer, it is recommended that the shallow foundations be founded below the estimated depth of frost penetration at 2.7 m (9.0 ft) to avoid frost heave. It is recommended that provisions be made for drainage around the foundation perimeter, to the depth of maximum frost penetration. However, the shallow foundation may be founded at a shallower depth if the superstructure can tolerate seasonal vertical movement. A properly designed thermal shield around the future building may also help to reduce the foundation depth.
The recommended allowable bearing capacity for a square and strip footing foundation from 0.0 m (0.0 ft) below ground to 4.6 m (15.0 ft) below ground and under are presented in Table 7.5. The recommended serviceability limited state (SLS) allowable bearing capacity is based on foundation settlement less than 25 mm (1 inch). For ultimate limit state (ULS) design, a resistance factor of 0.5 shall be applied on the ultimate bearing capacities given in the table. The self weight of the shallow foundation should be considered when determining the total capacity of the foundation.
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Table 7.5 – Ultimate and allowable bearing capacity for shallow foundations.
Depth Below Ground (m)
(ft)
0 to 1.5 1.5 to 3.0 3.0 to 4.6 4.6 and below
0 to 5 5 to 10 10 to 15 15 and below
Ultimate Bearing Capacity (kPa) 450 600 750 1020
Allowable Bearing Capacity (Estimated Settlement < 25 mm) (kPa) 150 200 250 250
Recommendations for shallow foundations are as follows:
It is anticipated that groundwater inflow may be encountered at shallow depths below ground during wet periods should shallow foundations be selected as the desired option. This is expected to represent challenges for the construction of shallow foundations, as it may be necessary to dewater any excavations prior to concrete forming and pouring and/or include construction of a concrete mud slab. It may be possible to construct a mat foundation at a relatively deeper depth (floating foundation). Should this option be selected, adequate measures will be required to keep the excavation free of water during construction. General recommendations for dewatering in a temporary excavation are given in Section 7.3.5 of this report. Shoring and/or bracing may also be required in order to reduce the excavation area or excavation volume. If so required, MDH will prepare additional recommendations for dewatering and shoring at Fortune Mineral’s request. The exposure of concrete to sulphate attack is classified as moderate to very severe at the site. A designer competent in concrete mix design should complete the concrete mix specifications. The self weight of the foundation shall be considered when determining the total capacity of the foundation.
The recommended coefficient of friction, at the base of footing is 0.38.
Shallow footing foundations may experience settlement after construction. The total settlement will be affected by the size, shape and founding depth of the footing, rigidity of the footing, geology and soil characteristics. The estimated total settlement vs. applied pressure for various sizes of square footings founded at 3 m (10 ft) below ground is provided in Figure 7.2.
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45
40
Estimated Settlement (mm)
35
30
25
20
15
12 ft
10
10 ft 8 ft 5
6 ft
0 50
100
150
200
250
300
350
Applied Pressure (kPa)
Figure 7.2 – Estimated settlement vs. applied presure for various sized square footing found at 10 ft below ground. 7.10.2 Grade Supported Floor Slabs It is anticipated that a grade supported floor slab may be required as part of the construction work, which should be supported on a prepared subgrade as recommended in Section 7.5 of this report. The recommended allowable bearing capacity of a grade supported floor slab shall follow the recommended values given in Table 7.5. It should be recognized that exterior grade-supported slabs will be subjected to vertical movements due to frost action and therefore such slabs should be free floating and should not be tied into the grade beams, pile caps or the interior slabs. Where the vertical movement of equipment or facilities on grade supported concrete slabs will be critical to operations, consideration should be given to the installation of structural floor systems supported on separate foundations. The silt near ground surface has medium to high swelling potential and the total volume change can be up to 15% and the clay near ground surface has very high swelling potential, the total volume change can be up to 40% (After Holtz and Gibbs, 1956).
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Mechanical equipment supported on the floor slab should contain provisions for re-leveling. Piping and electrical conduits should be laid out to permit some flexibility. A designer competent in concrete mix design should complete the specifications for the concrete mix. 7.10.3 Pile Foundations Pile foundations may be selected for the support of the plant buildings. The use of bored cast-in-place concrete friction-type piles is anticipated due to the soil characteristics of the site. Driven steel pile and continuous helical screwed piles may not be suitable options due to the potential presence of rock in the glacial till soil. The ultimate and allowable skin friction and end bearing values for general pile design are given in Table 7.6. Table 7.6 – General design parameters for bored, cast-in-place pile foundations. Ultimate Shaft Resistance (m) (ft) (kPa) 0 to 10 0 to 3.0 10 to 15 3.0 to 4.6 50 15 to 35 4.6 to 10.7 66 35 and below 10.7 and below 75 Depth Below Ground
Allowable Ultimate End Allowable Bearing End Bearing Shaft Capacity Capacity Resistance (kPa) (FS=3.0) (FS=2.0) 25 750 250 33 1275 425 37 1800 600
The above values are considered applicable for downward (compressive) static loads. The factored geotechnical axial capacity at ultimate limit states (ULS) should be taken as the ultimate axial capacity multiplied by the geotechnical resistance factor of 0.4 for compression and 0.3 for tension. The following recommendations for cast-in-place pile design should be considered:
It is recommended to limit the pile depth to 13.7 m (45 ft) below ground level, as there is a wet sand layer at approximately 15.2 m (50 ft) below ground. For resistance of uplift loads (such as frost), it is recommended to use 70 percent of the allowable static skin friction parameters provided. The self weight of the pile should be considered when determining the total capacity of the pile. Shaft friction should be neglected in the upper 1.5 m (5 ft) of the pile below finished ground surface due to soil desiccation effects. Should fill soils be encountered, the skin friction should be neglected for the entire depth of fill and the pile lengthened accordingly. Piles subjected to dynamic loads or uplift loads including frost should have a minimum length of 6.0 m (19.7 ft) and should be reinforced over their entire length.
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There is a potential for seepage and/or sloughing during pile drilling of bored concrete pile. It is recommended to have casing available on site and if necessary, to control groundwater seepage and/or caving conditions. Concrete shall be fed to the bottom of the drilled shaft by pumping and filled from bottom up or, using the free fall method or, another method approved by the structural engineer. If the free fall method is used, the concrete must be poured through a centering chute, making it fall down the centre of the hole, so that it does not hit the reinforcing steel or the side of the shaft. This results in adequate compaction below the upper 1.5 m. Vibration of the concrete in the upper 3.0 m near ground surface is required to produce uniform strength concrete. Pile excavations should be filled with concrete as soon as possible after drilling of the pile hole to reduce the risk of groundwater seepage and/or sloughing soil. Water should not be allowed to accumulate in the pile excavation and should be removed by pumping prior to pouring concrete.
It is recommended that the installation of piles be monitored by qualified geotechnical personnel to verify that the piles are properly installed and embedded into the appropriate soil stratum. The recommendations provided herein, for the design and construction of pile foundations should be reviewed and revised as required, once the structures and grade elevations have been identified and established. Pile Group Effects
If pile groups are required to achieve the required structural capacity, the minimum centre-to-centre pile spacing for cast-in-place concrete piles should be 3 times the pile diameter. The group efficiency of a friction pile group will be affected by the number of piles, the pile layout and pile diameters. Group efficiency factors for compressive loads need not be applied to groups of two or three piles, however, reduction in pile capacity would be required for larger groups. For centre-to-centre pile spacing greater than 7 pile diameters, the group efficiency is equal to 1.0 (i.e., no reduction in pile capacity for group effect). Group efficiency values are presented in Table 7.7 for some typical pile groups. MDH is available for further consultation on the issue of pile group efficiency if required, once a preliminary pile layout is determined.
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Table 7.7 – Typical group efficiency for 3x3 and 9x9 pile groups (After NAVFAV 7.02). Pile Group 3x3 9x9 3x3 9x9 3x3 9x9 3x3 9x9
Centre-to Centre Pile Spacing (pile diameter) 3 3 4 4 3 3 4 4
Pile Length (m) 22 22 22 22 11 11 11 11
Pile Diameter (m) 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45
Group Efficiency 0.75 0.71 0.80 0.77 0.80 0.76 0.87 0.85
7.10.4 Frost Action and Foundations The volume increase that occurs when water changes to ice is one of the causes of frost heave, but it is also recognized that a phenomenon known as ice segregation is the predominant mechanism: water is drawn from unfrozen soil to the freezing zone where it accumulates to form layers of ice, forcing soil particles apart and causing the soil surface to heave. A different form of frost action, called ‘adfreezing’, occurs when soil freezes to the surface of a foundation. Heaving pressures developing at the base of the freezing zone are transmitted through the adfreezing bond to the foundation, producing uplift forces capable of appreciable vertical displacements. Relatively little is known of the magnitude of the forces that may be generated, but bond strengths of adfreezing of 100 kPa (15 lb/in2) for steel surfaces and 70 kPa (10 lb/in2) for wood and concrete have been measured. It is recommended that void forms be used below grade beams (considering also the depth of frost penetration and location of the water table), and that they be designed to accommodate the possible jack force and volume change due to frost heave below the structure. The recommended minimum thickness of the void is 75 mm (3.0 inch). The finished grade adjacent to each grade beam should be capped with well compacted clay or other low permeable material and sloped away so that the surface runoff is not allowed to infiltrate and collect in the void space. If water is allowed to accumulate in the void space, the beneficial effect will be negated and frost heaving pressures will occur.
7.11 Seismic Design Ground Motions 7.11.1 Seismic Considerations The Canadian Foundation Engineering Manual (Canadian Geotechnical Society 2006) emphasizes that earthquake shaking is an important source of external load that must be considered in the design of civil engineering structures. The level of importance of earthquake loading at any given site is related to factors such as the subsoil conditions and M2112-2840010 Page 29
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behaviour, the 2005 National Building Code of Canada (NBCC) (National Research Council of Canada, 2005) are based on a 2% probability of exceedance in 50 years (return period of 2,475 years). This means that within a 50 year period, there is a 2% chance that the ground motions specified in the 2005 NBCC will be exceeded. 7.11.2 Site Soil Classification The site soil classification was determined from the energy-corrected average Standard Penetration resistance (N60). Based on the results of the subsurface exploration, the site is classified as Class C (i.e., very dense soil and soft rock profile or N60 > 50). 7.11.3 Site Spectral Acceleration The parameters used to represent seismic hazard for specific geographical locations are the 5% damped spectral acceleration values, Sa(T), for 0.2, 0.5, 1.0, and 2.0 second periods and the Peak Horizontal Ground Acceleration (PHGA) value that have a 2% probability of being exceeded in 50 years. In order to determine the design spectral acceleration values for the project site, the PHGA and the 5% damped spectral response acceleration values for the reference ground conditions (Site Class C) (i.e., very dense soil and soft rock profile or N60 > 50) need to be determined. Using the 2005 NBCC seismic hazard value interpolator obtained from the Natural Resources Canada website, the spectral acceleration values corresponding to the Class C soil profile were obtained. The spectral acceleration values for the reference ground conditions are tabulated in Table 7.8. Table 7.8 – Damped spectral acceleration for 2% probability of exceedance in 50 Years. Period (Sec)
Spectral Acceleration as a fraction of gravity Reference site Class C (Very dense soil and soft rock)
0
0.059
0.2
0.116
0.5
0.056
1.0
0.023
2.0
0.006
7.11.4 Uniform Hazard Spectra The four spectral parameters, including the PHGA define the Uniform Hazard Spectra (UHS). The UHS for the reference ground conditions (Class C) is shown in Figure 7.3.
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0.14
Spectral Acceleration, 5% damped (g)
June 2010
Reference Ground Conditions (Site Class C)
0.12 0.10 0.08 0.06 0.04 0.02 0.00 0
0.5
1
1.5
2
Period (seconds)
Figure 7.3 – Uniform hazard spectrum for 2% probability of exceedance in 50 Years.
7.12 Modulus of Vertical Subgrade Reaction, ks The modulus of subgrade reaction, ks is a conceptual relationship between soil pressure and deflection that is widely used in the structural analysis of foundation members. The modulus of vertical subgrade reaction can also be determined by using the testing result from plate loading test on site. However, the foundation designer may approximate the ks by the following formula: ks = 40 x FOS x qa where: FOS qa
= Factor of Safety = 3.0 = allowable bearing capacity = recommended values in Table 7.5.
MDH is available to provide plate loading test consulting service for the determination of the field measured subgrade reaction if required by Fortune Minerals.
7.13 Modulus of Horizontal Subgrade Reaction, kh The horizontal subgrade reaction, ks for fine grained soils from 0 m (0 ft) to 3.0 m (10 ft) below ground, kh = 6,700 kN/m3 and the fine grained silt till from 3.0 m (10 ft) and below, kh = 15,000 kN/m3. Please note that the above values of kh are appropriate for pile deflections at the ground line of 6 mm or less. For larger ground line deflections, these values may need to be reduced to account for the non-linear response of the soil adjacent to the pile. If the lateral loads are
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large and critical (with ground line deflections exceeding 6 mm), the analysis of laterally loaded piles should be conducted using a method that takes into account non-linear soil response such as Reese’s method of p-y curves. MDH is available to provide p-y curves if required by Fortune Minerals. The Group reduction factor for kh is summarized in Table 7.9. Table 7.9 – Group reduction factor for modulus of horizontal subgrade reaction, kh. Centre-to-Centre Pile Spacing in Direction of Load
Group Reduction Factor for Modulus of Subgrade Reaction
3d
0.25
4d
0.40
6d
0.70
8d (after Davisson, 1970)
1.00
The recommended modulus of subgrade reaction are for both vertical pile and batter pile.
7.14 Foundation Concrete The water-soluble sulphate content of six representative soil samples was determined in the laboratory by ALS Group in Saskatoon, SK. The tests showed the presence of 58 mg/L to 15,182 mg/L of water-soluble sulphate (SO4) content in the soil samples, indicating that there is a moderate to very severe degree of exposure to sulphate attack as per Table 3.0 of CSA A23.1-04. A wide variety of CSA concrete types (HS, HSb, MS, MSb and LH) were recommended in the table. The recommendations stated above for the subsurface concrete at this site may require further additions and/or modifications due to structural, durability, service life or other considerations which are beyond the geotechnical scope. A designer competent in concrete mix design should complete the specifications for the concrete mix. In addition, if imported fill material is required to be used at the site and will be in contact with concrete, it is recommended that the fill soil be tested for sulphate content to determine whether the above-stated recommendations remain valid.
7.15 Paved Areas 7.15.1 Pavement Subgrade Strength The characteristic material property of subgrade soils used for pavement design is the resilient modulus (MR). The MR is defined as a measure of the elastic property of a soil M2112-2840010 Page 32
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recognizing selected non-linear characteristics. Using the Group Index of soil to determine the California Bearing Ratio (CBR) and MR is a standard method use in Saskatchewan. A separate report will provide pavement surfacing design for the site roadways and parking areas.
8.0 Construction Control and Monitoring All recommendations presented in this report are based on the assumption that full time inspection, monitoring, and control testing are provided by qualified geotechnical personnel(s) during site grading and clearing, construction and foundation installation. Hence, quality control should be provided as follows:
Full time inspection during site grading, clearing and excavation to verify the removal of unsuitable materials. Full time in-situ density and moisture content testing should be carried out during subgrade preparation, and placement of fill. Full time in-situ density and moisture content testing should be provided during utility backfill. Full time inspection during footing or pile construction.
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9.0 Closure MDH Engineered Solutions Corp., hereinafter collectively referred to as “MDH”, has exercised reasonable skill, care and diligence in preparing this report. MDH will not be liable under any circumstances for the direct or indirect damages incurred by any individual or entity due to the contents of this report, omissions and/or errors within, or use thereof, including damages resulting from loss of data, loss of profits, loss of use, interruption of business, indirect, special, incidental or consequential damages, even if advised of the possibility of such damage. This limitation of liability will apply regardless of the form of action, whether in contract or tort, including negligence. MDH has prepared this report for the exclusive use of Fortune Minerals Limited and the representatives of Fortune Minerals Limited, and does not accept any responsibility for the use of this report for any purpose other than intended. Any alternative use, reliance on, or decisions made based on this document are the responsibility of the alternative user or third party. MDH accepts no responsibility to any third party for the whole or part of the contents and exercise no duty of care in relation to this report. MDH accepts no responsibility for damages suffered by any third party as a result of decisions made or actions based on this report. Should you have any questions or comments please contact us. Regards, MDH Engineered Solutions Corp.
Association of Professional Engineers And Geoscientists of Saskatchewan Certificate of Authorization Number 662
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9.0 Closure MDH Engineered Solutions Corp., hereinafter collectively referred to as “MDH”, has exercised reasonable skill, care and diligence in preparing this report. MDH will not be liable under any circumstances for the direct or indirect damages incurred by any individual or entity due to the contents of this report, omissions and/or errors within, or use thereof, including damages resulting from loss of data, loss of profits, loss of use, interruption of business, indirect, special, incidental or consequential damages, even if advised of the possibility of such damage. This limitation of liability will apply regardless of the form of action, whether in contract or tort, including negligence. MDH has prepared this report for the exclusive use of Fortune Minerals Limited and the representatives of Fortune Minerals Limited, and does not accept any responsibility for the use of this report for any purpose other than intended. Any alternative use, reliance on, or decisions made based on this document are the responsibility of the alternative user or third party. MDH accepts no responsibility to any third party for the whole or part of the contents and exercise no duty of care in relation to this report. MDH accepts no responsibility for damages suffered by any third party as a result of decisions made or actions based on this report. Should you have any questions or comments please contact us. Regards, MDH Engineered Solutions Corp.
Association of Professional Engineers And Geoscientists of Saskatchewan Certificate of Authorization Number 662
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10.0 References Canadian Geotechnical Society (CGS), 2006, Canadian Foundation Engineering Manual 4th Edition. 488 pp. CSA A23.1-04, Concrete materials and methods of concrete construction, CSA, 2004 Earthquakes Canada website (http://earthquakescanada.nrcan.gc.ca), accessed January 8, 2008. NBCC, 2005, User’s Guide – NCB 2005, Structural Commentaries (Part 4 of Division B). Canadian Commission on Building and Fire Codes. National Research Council of Canada. Donald P Coduto, Foundation Design, Principles & Practices, 2nd Ed. Prentice Hall Inc. ISBN 0-13-589706-8. Pavement Design Manual, Alberta Transportation and Utilities, Edition 1, June 1997. Pile Design and Construction Practise, M J Thomlinson, First Ed. Chapman & Hall. Bowles J E, Foundation Analysis and Design, Fifth Ed. McGraw-Hill International Ed., ISBN 0-07-118844-4. National Research Council Canada website, Canadian Building Digest, (http://irc.nrc-rc.gc.ca/pubs/cbd/cbd182_e.html), (http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd128_e.html) and (http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd156_e.html), CBD-128, CBD-182 and CBD-156, NRC-CNRC. Foundation and Earth Structures, Design Manual 7.02, 1986, Naval Facilities Engineering Command.
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TERMS, SYMBOLS AND ABBREVIATIONS
M2112-2840010 Appendices
Terms, Symbols and Abbreviations Field geological description of a soil is achieved through a brief description of the following points. All points should be included to accurately describe a soil for geoenvironmental applications: 1) 2) 3) 4) 5) 6)
Lithology/texture (size, proportion, and shape); Colour and oxidation; Consistency and plasticity (cohesive soils); Condition (non-cohesive soils); Moisture; and Other miscellaneous descriptors.
1)
Lithology / Texture
The texture of a soil is a combination of the size and shape of the particles and the relative proportions of each of the constituents (eg. subrounded to subangular gravel, sandy, some silt, trace cobble). Particle Size (ASTM D2487-85) Boulder 300mm plus Cobble 75 – 300 mm Gravel 4.75 – 75 mm Sand 0.075 – 4.75mm Fine: 0.075 – 0.425 mm Medium: 0.425 – 2 mm Coarse: 2 – 4.75 mm Rounded Subrounded Subangular Angular
Particle Shape (coarse grained soils) No edges and smoothly curved sides Well-rounded corners and edges, nearly plane sides Similar to angular but have rounded edges Sharp edges and relatively plane sides with unpolished surfaces
Well Graded Uniform (Poorly Graded) Gap Graded
2)
Relative Proportions (by weight) Parent Material >35% and main fraction Modifier 20 – 35% eg: gravely, sandy, silty, clayey, etc. Some 10 – 20% Trace 0 – 10%
Gradation (coarse grained soils) Having a wide range of grain sizes and substantial amount of all intermediate sizes Possessing particles of predominantly one size Possessing particles of several distinct sizes
Colour and Oxidation
A soils colour may be described either qualitatively in the field at the soils natural moisture content using common colours (eg. light grey, light brown, dark grey, etc.) or quantitatively by comparison with a colour chart. Soils colour is typically quantified using a Munsell Book of Colour. The soil colour description is characterized by a combination of hue, value and chroma. The hue notation of a colour indicates its relation to red, yellow, green, blue and purple; the value notation indicates its lightness; and the chroma notation indicates its strength (or departure from a neutral of the same lightness (eg 2.5Y 4/2). Quantitative determination of colour using a Munsell Book of Colours is completed after the soil has been allowed to dry at a low temperature. When a soil is exposed to an oxygen rich environment it oxidizes and the soils colour departs from neutral (eg from dark grey-5Y 4/1 to dark reddish brown-5Y4/2). The colour change is generally a result of iron oxidation and staining (red) or manganese staining (purple to black). The oxidation may occur throughout the entire soil mass or commonly as fracture and joint coatings and haloes.
3)
Consistency and Plasticity (Cohesive Soils)
The consistency of a soil is a qualitative description of a cohesive soils ability to resist deformation and may be correlated to the undrained shear strength. Consistency and undrained shear strength (Su) of a soil may be field-tested using the thumb and thumbnail or more accurately with a pocket penetrometer. The plasticity of a soil is a measure of the soils ability to deform without rupture. The plasticity of a cohesive soil should be estimated as low (LL