Stress history and time effect on shear modulus of expansive soils

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Jingjing Li ◽  
Lingwei Kong ◽  
Lei Jin
Keyword(s):  
Shear Modulus ◽  
Expansive Soils ◽  
Time Effect ◽  
Stress History

Shear modulus and damping of soft Bangkok clays

2002 ◽  
Vol 39 (5) ◽  
pp. 1201-1208 ◽  
Author(s):  
Supot Teachavorasinskun ◽  
Pipat Thongchim ◽  
Panitan Lukkunaprasit
Keyword(s):  
Shear Modulus ◽  
Seismic Analysis ◽  
Damping Ratio ◽  
Soft Clay ◽  
Cyclic Stress ◽  
Large Strains ◽  
Cyclic Triaxial ◽  
Stress History ◽  
Load Frequency ◽  
Equivalent Shear Modulus

The shear modulus and damping ratio of undisturbed Bangkok clay samples were measured using a cyclic triaxial apparatus. Although abundant literature on this topic exists, selection of the most suitable empirical correlation for a seismic analysis cannot be done unless site specific data are obtained. The apparatus used in this research can measure the stress–strain relationships from strain levels of about 0.01%. The equivalent shear modulus measured at these strains was about 80% of the value obtained from the shear wave velocity measurements. The degradation curves of the equivalent shear modulus fell into the ranges reported in the literature, for clay having similar plasticity. The damping ratios varied from about 4–5% at small strains (0.01%) to about 25–30% at large strains (10%). The effects of load frequency and cyclic stress history on the shear modulus and damping ratio were also investigated. An increase in load frequency from 0.1 to 1.0 Hz had no influence on the shear modulus characteristic, but it did result in a slight decrease in the damping ratio. The effects of the small amplitude cyclic stress history on the subsequently measured shear modulus and damping ratio were almost negligible when the changes in void ratio were taken into account.Key words: soft clay, shear modulus, damping ratio, cyclic triaxial test, cyclic stress history.

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.

Shear Modulus and Damping of Peat Subjected to Overconsolidation Stress History

2020 ◽  
Vol 38 (6) ◽  
pp. 6421-6430
Author(s):  
Hirochika Hayashi ◽  
Osamu Hatakeyama ◽  
Hijiri Hashimoto ◽  
Masahiko Yamaki
Keyword(s):  
Shear Modulus ◽  
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°.

scholarly journals Stress-History Effects on Shear Modulus of Soils

1973 ◽  
Vol 13 (1) ◽  
pp. 77-95 ◽  
Author(s):  
S.S. Afifi ◽  
F.E. Richart
Keyword(s):  
Shear Modulus ◽  
Stress History ◽  
History Effects
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