Experimental study of effects of suction history and wetting-drying on small strain stiffness of an unsaturated soil

2011 ◽  
Author(s):  
Jie Xu
Keyword(s):  
Experimental Study ◽  
Unsaturated Soil ◽  
Small Strain ◽  
Small Strain Stiffness ◽  
Suction History

Modelling the influence of stress–strain history on the initial shear stiffness of an unsaturated compacted silt

2007 ◽  
Vol 44 (4) ◽  
pp. 463-472 ◽  
Author(s):  
Roberto Vassallo ◽  
Claudio Mancuso ◽  
Filippo Vinale
Keyword(s):  
Unsaturated Soil ◽  
Shear Stiffness ◽  
Small Strain ◽  
Complex Stress ◽  
Strain History ◽  
Strain Behaviour ◽  
Observed Behaviour ◽  
Suction History ◽  
Simple Stress

This is the follow-up paper to Vassallo et al. (2007), which discussed the experimentally observed small-strain behaviour of an unsaturated compacted silt. The influence that suction and, more in general, mean net stress – suction history has on the initial shear stiffness was analysed and ascribed to the accumulation of irreversible volumetric strains. In this study, a model able to predict the observed behaviour is proposed, based on classical unsaturated soil volumetric hardening elastoplastic formulations. Starting from the interpretation of the results relative to simple stress paths, such as preliminary equalization and loading–unloading compression, the results of "complex" stress paths, such as those including drying–wetting cycles, have subsequently been modelled by introducing some additional parameters.Key words: unsaturated, compacted, small strain, stiffness, volumetric behaviour, stress history.

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°.

Effects of net stress and suction history on the small strain stiffness of a compacted clayey silt

2007 ◽  
Vol 44 (4) ◽  
pp. 447-462 ◽  
Author(s):  
Roberto Vassallo ◽  
Claudio Mancuso ◽  
Filippo Vinale
Keyword(s):  
Shear Stiffness ◽  
Small Strain ◽  
Resonant Column ◽  
Stress History ◽  
Small Strain Stiffness ◽  
Maximum Value ◽  
Clayey Silt ◽  
Triaxial Cell ◽  
The Mean ◽  
Suction History

An experimental study was carried out to investigate the effects of the mean net stress and suction history on the initial shear stiffness, G0, of a compacted clayey silt. Isotropic tests were performed using two suction-controlled devices, a triaxial cell and a resonant column torsional shear (RCTS) cell, so as to investigate the volumetric behaviour of this material. As for saturated soils, one can expect to find a strong correlation among stress history, volumetric state, and G0. Initial shear stiffness was measured almost continuously along various isotropic stress paths, including compressions and drying–wetting single stages or cycles, by using the RCTS cell. The collected data demonstrate a strong dependency of G0 on mean net stress (p – ua) and suction (ua – uw). Cycles of suction, in particular increasing suction beyond the past maximum value, induce significant accumulation of irreversible strains and increase of stiffness, confirming that G0 is not univocally related to the stress state (p – ua, ua – uw).Key words: unsaturated, compacted, small strain, stiffness, volumetric behaviour, stress history.

scholarly journals Estimation of the Small-Strain Stiffness of Clean and Silty Sands using Stress-Strain Curves and CPT Cone Resistance

2009 ◽  
Vol 49 (4) ◽  
pp. 545-556 ◽  
Author(s):  
Junhwan Lee ◽  
Doohyun Kyung ◽  
Bumjoo Kim ◽  
Monica Prezzi
Keyword(s):  
Small Strain ◽  
Stress Strain ◽  
Cone Resistance ◽  
Small Strain Stiffness

scholarly journals Effect of cementation on the small-strain stiffness of granite residual soil

2021 ◽  
Vol 61 (2) ◽  
pp. 520-532
Author(s):  
Xinyu Liu ◽  
Xianwei Zhang ◽  
Lingwei Kong ◽  
Xinming Li ◽  
Gang Wang
Keyword(s):  
Small Strain ◽  
Residual Soil ◽  
Small Strain Stiffness ◽  
Granite Residual Soil

Small strain stiffness of carbonate Kenya Sand

2013 ◽  
Vol 161 ◽  
pp. 65-80 ◽  
Author(s):  
V. Fioravante ◽  
D. Giretti ◽  
M. Jamiolkowski
Keyword(s):  
Small Strain ◽  
Small Strain Stiffness

Small strain stiffness for granite residual soil: effect of stress ratio

2021 ◽  
Author(s):  
Xianwei Zhang ◽  
Xinyu Liu ◽  
Lingwei Kong ◽  
Gang Wang ◽  
Cheng Chen
Keyword(s):  
Stress Ratio ◽  
Small Strain ◽  
Residual Soil ◽  
Resonant Column ◽  
Residual Soils ◽  
Column Tests ◽  
Small Strain Stiffness ◽  
Deviator Stress ◽  
Granite Residual Soil ◽  
Stress Ratios

Most previous studies have focused on the small strain stiffness of sedimentary soil while little attention has been given to residual soils with different properties. Most studies also neglected the effects of the deviator stress, which is extensively involved in civil engineering. This note considers the effects of the deviator stress on the small-strain stiffness of natural granite residual soil (GRS) as established from resonant column tests performed under various stress ratios. Although increasing the stress ratio results in a greater maximum shear modulus for both natural and remolded residual soils, remolded soil is more sensitive to changes in the stress ratio, which highlights the effects of soil cementation. The data herein offers new insights to understand the stiffness of residual soil and other weathered geomaterials.

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