International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 12, December 2017, pp. 77–88, Article ID: IJCIET_08_12_009 Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=12 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication
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REGIONAL NORMALIZED EMPIRICAL CORRELATIONS FOR THE COMPRESSION INDEX (Cc) OF SOIL – A CRITICAL OVERVIEW Chandra Bogireddy Research Scholar, Applied Mechanics, Department, S.V. NIT, Surat, Gujarat, India Ganesh Sutar Postgraduate Student, Applied Mechanics Department, S.V.NIT, Surat, Gujarat Solanki. C. H Professor & Head, Applied Mechanics Department, S.V.NIT, Surat, Gujarat, India Vasanwala. S. A Professor, Applied Mechanics Department, S.V.NIT, Surat, Gujarat, India ABSTRACT Laboratory one dimensional consolidation test is used to find out one of the important consolidation parameter of cohesive soils i.e., compression index (Cc) and, which plays a pivotal role in the design aspect of all underground structures based on settlement criteria. Several researchers have focused to correlate compression index with various index properties in terms of single and multiple regressions on regional soils. These correlations are not generalized and have some limitations due to varying soil properties. Since the existence of soil is different from place to place due to with geographic region and/or geological origin. In this paper an attempt has been made to present the regional empirical correlations proposed by various researchers for compression index based on critical overview. The accumulated review results may useful to quick identification of regional empirical equations to estimate the conventional compression as per the limitations. Keywords: Compression index (Cc), Critical overview, Empirical correlations, Regional soil Cite this Article: Chandra Bogireddy, Ganesh Sutar, Solanki. C. H and Vasanwala. S. A, Regional Normalized Empirical Correlations for the Compression Index (Cc) of Soil–A Critical Overview, International Journal of Civil Engineering and Technology, 8(12), 2017, pp. 77–88 http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=12
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Regional Normalized Empirical Correlations for the Compression Index (Cc) Of Soil – A Critical Overview
1. INTRODUCTION Consolidation is the process in which soil particles are packed more closely together over a period of time under the application of continued vertical stress i.e., static loading. It is achieved mainly by gradual drainage of water from the soil pores. Consolidation occurs to saturated or nearly saturated clays or other soils of low permeability. This process normally involves incremental loading on the soil sample and measuring the corresponding settlements. This consolidation characteristic is encountered in various areas of geotechnical to analyze and design of structural footings, pile foundations, embankments and earth retaining structures in the settlement criteria. A laboratory experiment, 1-D consolidation is carried out by oedometer test to determine the one of the important consolidation characteristics i.e., compression index (Cc) has used to find out and this test method is primarily proposed by Terzaghi in 1923 [1]. This test is carried out based on the standard consolidation test, i.e., incremental loading test (ASTM D2435-11 2011 [2]) or constant rate of strain test (ASTM D4186-12 2012 [3]). The Cc, is the slope of the compression curve in terms of void ratio e versus vertical effective stress σv' in the semi-logarithmic plane, which is determined based on the equation (1), ∆e Cc = − ∆(logσ ' ) (Eq.1) Where, ∆e is the change in the void ratio per logarithmic cycle of stress. The settlement associated with load increments is generally determined directly using the compression index Cc determined from the e-logσv' curve. For a layer of normally consolidated clay of thickness H, initial void ratio eo, compression index, and effective overburden pressure σo′, the total settlement Sc under an applied load increment ∆σ′ can be expressed as equation (2), σ ' 0 +∆σ ' C S c = − c H log 1 + eo σ '0 (Eq.2) The laboratory oedometer test takes abundant time to determine Cc more than 15 days in case of highly compressible with a low coefficient of consolidation of soils and it requires more efforts [4]. The numerical evaluation of soil properties has always attracted the interest of geotechnical engineers. The reason for this enthusiasm is the wish to establish correlations between various soil parameters in order to estimate the behavior of soil layers approximately without going through detailed testing and evaluation stages [5]. The first ever empirical correlation for determining compression index based on liquid limit for remoulded clays was presented by Skempton in 1944 [6] and further Terzaghi & Peck (1967) [7] presented a modified equation for normally consolidated clays. Several researchers have tends to correlate compression index with various index properties in terms of single and multiple regressions (such as liquid limit, plastic limit, plasticity index, water content, void ratio etc.,), but most of these investigations were of regional clays and other mineral soils [example, 6-15]. These correlations are not generalized and have some limitations due to varying soil properties [8]. Since the existence of soil is different from place to place due to with geographic region and/or geological origin. In this present paper, the regional empirical correlations proposed by various researchers on compression index are summarized based on critical overview. These review results may useful to quick identification of regional empirical equations to estimate the conventional compression as per the limitations.
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Chandra Bogireddy, Ganesh Sutar, Solanki. C. H and Vasanwala. S. A
2. EMPIRICAL EQUATIONS DEVELOPED BY VARIOUS RESEARCHERS In literature, several correlations have been proposed for soil compressibility characteristics such as compression index Cc with index properties in terms of single and multiple regressions using liquid limit, natural moisture content, initial void ratio, plasticity index, specific gravity, void ratio at liquid limit, and several other properties of soil (example Cc = f (wL , wn , eo , I p , Gs , γ d , γ w, γ d max, DFS) . The summarized empirical equations are presented in Table 1 to 6 based on the critical overview. The empirical equations developed by various researchers are summarized as per the region/conditions of applicability and theses equations are as follows: Table 1 Compression index equations with function of liquid limit; Cc = f (wL ) Eq. No.
Empirical Equations
Reference
Region/Conditions of Applicability
1.
Cc = 0.007 (wL −10)
Skempton (1944) [6]
Remoulded clays, (Normally consolidated, St < 1.5)
2
Cc = 0.01( wL −12)
Murayama et al. (1958) [9]
Osaka alluvial clays
3
Cc = 0.013( wL −13.5)
Yamagutshi (1959) [10]
All clays
4
Cc = 0.013wL
Kyushu Branch of JSSMFE (1959) [11]
Ariake clay
5
Cc = 0.014( wL − 20)
Taniguchi et al. (1960) [12]
Ishikari clay
6
Cc = 0.0046 ( wL − 9)
Cozzolino (1961) [13]
Brazilian clays
7
Cc = 0.004( wL − 10)
Taniguchi (1962) [14]
Rumoi clay
8
Cc = 0.017 (wL − 20)
Shouka (1964) [15]
All clays
9
Cc = 0.009 ( wL − 10)
Terzaghi & Peck (1967) [7]
Normally consolidated, (Moderately sensitive, St < 5)
10
Cc = 0.0083 ( wL − 9)
Schofield and Wroth (1968) [16]
Various clays
Beverly (1975) [17]
Blake-Bahama Outer Ridge Area deep-sediments
11
Cc = −0.0051(wL2 + 0.1328wL − 6.412)
12
Cc = 0.0046 ( wL − 9)
Azzouz et. al. (1976) [18]
Brazilian clay, (Moderately Overconsolidated)
13
Cc = 0.006 ( wL − 9)
Azzouz et al. (1976) [18]
All clays with wL< 100%
14
Cc = 0.0092(wL − 13)
Mayne (1980) [19]
Various clays
15
C c = 0.008 ( wL − 10)
Burghignoli & Scarpelli (1985) [20]
Italian soft clays
16
Cc = 0.0046 ( wL − 9)
Bowles (1989) [21]
Brazilian clays; (Moderately overconsolidated)
17
Cc = 0.01( wL − 0.063)
Hirata et al. (1990) [22]
Natural soils (cohesive)
18
Cc = 0.063(wL − 10)
Abdrabbo & Mahmoud (1990) [23]
Egyptian clay
19
Cc = 0.009 ( wL − 8)
Tsuchida (1991) [24]
Osaka Bay clay
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Regional Normalized Empirical Correlations for the Compression Index (Cc) Of Soil – A Critical Overview 20
C c = 0.008( wL − 12)
Sridharan & Nagaraj (2000) [25]
All clays
21
C c = 0.006 ( w L + 1) , R 2 = 0.509
Lav & Ansal (2001) [5]
Soil in Turkey
22
Cc = 0.011(wL − 6.36)
Yoon et al. (2004) [8]
Marine costal clays, Korea
Solanki and Desai 2008 [26]
Alluvial deposits, Surat, India
Cc = 0.0046( wL −1.39)
Arpan & Sujit (2012) [27]
Soil in NIT Agartala campus and Howrah, India
Cc = 0.0055 ( wL − 1.8364) , R = 0.970
Vinod and Bindu (2010) [28]
Remoulded, highly plastic, marine clays, Kerala, India
26
Cc = 0.014wL − 0.168
Park and Lee (2011) [29]
Soils in Korea
27
Cc = 0.5217( wL − 1.30)
Widodo & Abdelazim (2012) [30]
Soil in Supadio Airport in Pondianak
R = 0.349
Widodo & Abdelazim (2012) [30]
Pontianak Soft Clay
29
Cc = 0.026 wL − 0.536 , R 2 = 0.939
Nesamatha and Arumairaj (2015) [31]
30
Cc = 0.0067wL − 0.0364, R 2 = 0.94
Kumar et al. (2016) [32]
31
Cc = 0.001wL − 0.013, R 2 = 0.863
Shiva and Darga Kumar (2016) [33]
23 24 25
28
Cc = 0.0061(wL − 0.0024) , R 2 = 0.8435
2
Cc = 0.01706(wL − 1.29) , 2
Remoulded clay sample, Coimbatore, India Black cotton soil. red soil and yellow soil, Bhopal, India Hyderabad, Andhra Pradesh (A.P.), India
Table 2 Compression index equations with function of plasticity index; Cc = f (I p ) Eq. No.
Empirical Equations
Reference
Region/ Conditions of Applicability
1.
C c = 0.02 + 0.014 ( I p )
Nacci et al. (1975) [34]
North Atlantic clay
2.
Cc =1.325 (I p )
Wroth and Wood (1978) [35]
Remoulded clays
3.
Cc = I p 74
Wroth and Wood (1978) [35]
All clays
4
Cc =1.325 (I p )
Koppula (1981) [36]
Remoulded clays
5
Cc = 0.104 (I p ) + 0.46
Nakase et al. (1988) [37]
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