Small-Strain Shear Modulus of Calcareous Sand under Anisotropic Consolidation

In this study, the small strain shear modulus of a calcareous sand was investigated by conducting bender element tests on both horizontal and vertical planes. The effects of sample preparation method, stress path and stress history on the developing of void ratio, the parameters in the modified Hardin equation and the stiffness anisotropy were examined. The test results show that the moist tamping samples have the least void ratio variation among the five samples. The void ratio recovery in σ'h = 100 kPa tests is higher than that in the σ'v = 100 kPa tests. The samples prepared in dry state have lower stiffness than those prepared in moisture state, which is not influenced by the anisotropic stress state. The stiffness anisotropy induced by the sample preparation method is significant under anisotropic consolidation. In σ'h = 100 kPa tests, the stiffness ratios at the end of the unloading stage are lower than the initial values at the loading stage, which is not found in the σ'v = 100 kPa tests, meaning that the stress history and stress path could affect the stiffness anisotropy and cover the impact of fabric anisotropy.

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Predicting the Small Strain Stiffness of a Calcareous Sand Considering Sample Preparation Method and Stress Path

Smart and Green Solutions for Civil Infrastructures Incorporating Geological and Geotechnical Aspects - Sustainable Civil Infrastructures ◽

10.1007/978-3-030-79650-1_6 ◽

2021 ◽

pp. 70-77

Author(s):

Jinquan Shi ◽

Wim Haegeman

Keyword(s):

Sample Preparation ◽

Preparation Method ◽

Stress Path ◽

Small Strain ◽

Sample Preparation Method ◽

Calcareous Sand ◽

Small Strain Stiffness

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

E3S Web of Conferences ◽

10.1051/e3sconf/20199204005 ◽

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.

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