Effects of current suction ratio and recent suction history on small-strain behaviour of an unsaturated soil

2012 ◽  
Vol 49 (2) ◽  
pp. 226-243 ◽  
Author(s):  
C.W.W. Ng ◽  
J. Xu
Keyword(s):  
Shear Modulus ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Small Strain ◽  
Triaxial Tests ◽  
Stress History ◽  
Reduction Curve ◽  
Small Strain Shear Modulus ◽  
Suction History ◽  
Modulus Reduction

Although the small-strain shear modulus of saturated soils is known to be significantly affected by stress history, consisting of the overconsolidation ratio (OCR) and recent stress history, the effects of suction history on the small-strain shear modulus of unsaturated soils have rarely been reported. In this study, the effects of suction history, which refers to current suction ratio (CSR) and recent suction history, on both the very-small-strain shear modulus (G0) and shear modulus reduction curve of an unsaturated soil, are investigated by carrying out constant net mean stress compression triaxial tests with bender elements and local strain measurements. In addition, the effect of suction magnitude on G0 and the shear modulus reduction curve is also investigated. At a given suction, G0, elastic threshold strain (εe), and the rate of shear modulus reduction all increase with CSR. On the other hand, the effect of recent suction history on G0 is not significant. The effect of direction of recent suction path (θ) on the shear modulus reduction curve is not distinct. However, the magnitude of recent suction path (l) affects the shear modulus reduction curve significantly when θ = –90°.

scholarly journals Temperature-Dependent Model for Small-Strain Shear Modulus of Unsaturated Soils

2020 ◽  
Vol 146 (12) ◽  
pp. 04020136
Author(s):  
Farshid Vahedifard ◽  
Sannith Kumar Thota ◽  
Toan Duc Cao ◽  
Radhavi Abeysiridara Samarakoon ◽  
John S. McCartney
Keyword(s):  
Shear Modulus ◽  
Unsaturated Soils ◽  
Small Strain ◽  
Temperature Dependent ◽  
Small Strain Shear Modulus ◽  
Dependent Model ◽  
Temperature Dependent Model

scholarly journals A semi-empirical relationship for the small-strain shear modulus of soft clays

2019 ◽  
Vol 92 ◽  
pp. 04005
Author(s):  
Vashish Taukoor ◽  
Cassandra J. Rutherford ◽  
Scott M. Olson
Keyword(s):  
Shear Modulus ◽  
Effective Stress ◽  
Void Ratio ◽  
Empirical Relationship ◽  
Small Strain ◽  
High Plasticity ◽  
Bender Element ◽  
Stress History ◽  
Small Strain Shear Modulus ◽  
Semi Empirical

The small-strain shear modulus (Gmax) is a soil property that has many practical applications. The authors compiled a database of Gmax measurements for 40 normally consolidated to slightly overconsolidated low to high plasticity clays. Using these data, the authors propose a semi-empirical relationship between Gmax, effective stress (σ'v or σ'c), preconsolidation stress (σ'p) and in-situ void ratio (e0) for four ranges of plasticity index (Ip): Ip < 30%, 30% ≤ Ip < 50%, 50% ≤ Ip < 80% and 80% ≤ Ip < 120%. With results from bender element tests on a Gulf of Mexico clay subjected to multiple load-unload consolidation loops, the authors were able to validate the proposed relationships for 30% ≤ Ip < 50% and 50% ≤ Ip < 80%. The proposed relationship for 30% ≤ Ip < 50% and 50% ≤ Ip < 80% captures changes in laboratory Gmax resulting from variations in effective stress (σ'c), maximum past stress (σ'v,max), and void ratio. The proposed relationships are a simple and efficient tool that can provide independent insight on Gmax if the stress history of a clay is known, or on stress history if Gmax is known.

scholarly journals Cyclic Loading Test for the Small-Strain Shear Modulus of Saturated Soft Clay and Its Failure Mechanism

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhende Zhu ◽  
Cong Zhang ◽  
Jun Wang ◽  
Peng Zhang ◽  
Duan Zhu
Keyword(s):  
Shear Stress ◽  
Shear Modulus ◽  
Effective Stress ◽  
Soft Clay ◽  
Small Strain ◽  
Triaxial Tests ◽  
Loading Test ◽  
Cyclic Shear ◽  
Small Strain Shear Modulus ◽  
Saturated Soft Clay

Small-strain shear modulus, G max , is a key evaluation index to study the dynamic characteristics of soil in geotechnical engineering. It is widely adopted to evaluate the stiffness of soft soil in soil dynamic engineering. In this paper, the cyclic triaxial tests and resonance column tests were carried out to explore the variation of G max of soft clay with respect to various confining stresses, cyclic shear stress ratios, pore pressures, and effective stress paths. Test results indicated that the effective stress decreased gradually with the increase of the cycle shear stress ratio. The failure points were mainly concentrated in a rectangular area, defined by the normalized effective stress from 0.56 to 0.64 and the normalized shear modulus from 0.72 to 0.78. Additionally, a short pause caused a small increase of 1-2% in G max as well as pore pressure. This study demonstrates that G max can be effectively used to characterize the failure of saturated soft clay in a more intuitive and convenient way, compared to the commonly used strain failure standards.

scholarly journals Impact of void ratio and state parameters on the small strain shear modulus of unsaturated soils

2016 ◽  
Vol 2 (4) ◽  
pp. 241-246 ◽  
Author(s):  
A. Khosravi ◽  
A. Gheibi ◽  
M. Rahimi ◽  
J. S. McCartney ◽  
S. M. Haeri
Keyword(s):  
Shear Modulus ◽  
Unsaturated Soils ◽  
Void Ratio ◽  
Small Strain ◽  
Small Strain Shear Modulus

Shear modulus and material damping of municipal solid waste based on large-scale cyclic triaxial testing

2008 ◽  
Vol 45 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Dimitrios Zekkos ◽  
Jonathan D. Bray ◽  
Michael F. Riemer
Keyword(s):  
Shear Modulus ◽  
Large Scale ◽  
Dynamic Properties ◽  
Small Strain ◽  
Unit Weight ◽  
Material Damping ◽  
Confining Stress ◽  
Small Strain Shear Modulus ◽  
Waste Composition ◽  
Modulus Reduction

Representative dynamic properties of municipal solid waste (MSW) are required to perform reliable seismic analyses of MSW landfills. A comprehensive large-scale cyclic triaxial laboratory testing program was performed on MSW retrieved from a landfill in the San Francisco Bay area to evaluate the small-strain shear modulus, and strain-dependent normalized shear modulus reduction and material damping ratio relationships of MSW. The effects of waste composition, confining stress, unit weight, time under confinement, and loading frequency on these dynamic properties were evaluated. The small-strain shear modulus depends primarily on waste composition, confining stress, unit weight, and time under confinement. The normalized shear modulus reduction and material damping curves for MSW depend on waste composition and confining stress. Based on the results of this study and a review of literature, strain-dependent shear modulus reduction and material damping relationships are recommended for use in landfill design.

Bender Element Measurement for Small-Strain Shear Modulus of Compacted Loess

2021 ◽  
Vol 21 (5) ◽  
pp. 04021063
Author(s):  
Fangtong Wang ◽  
Dianqing Li ◽  
Wenqi Du ◽  
Chia Zarei ◽  
Yong Liu
Keyword(s):  
Shear Modulus ◽  
Small Strain ◽  
Bender Element ◽  
Small Strain Shear Modulus ◽  
Compacted Loess
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