Effects of overconsolidation ratio and stress rate on unloading mechanical behavior of expansive clay
Author(s): LI Xin-ming, KONG Ling-wei, GUO Ai-guo, ZHOU Heng, ZHU Ming-hui
Pages: 121-127
Year: 2013 Issue: z2
Journal: Rock and Soil Mechanics
Keyword: expansive clay; overconsolidation; stress rate; stress paths; deformation modulus;
Abstract: A total number of 21 consolidated undrained triaxial shear tests on Nanyang expansive clay have been performed by GDS stress path triaxial system. The specimens are prepared in kinds of 4 different overconsolidation ratios (OCR) for reduced triaxial compression (RTC) shear tests and 3 for reduced triaxial tension (RTT) shear tests, which all sheared at three different stress relief rates. The influences of OCR and stress rate on stress-strain relationship, pore water pressure, effective stress path and deformation modulus are investigated. The results show that the influences of OCR and stress rate on mechanical behavior of expansive clay in compression and tension are similar. As the increase of stress rate and OCR, the deviatoric stress in stress-strain curve increased monotonically to the maximum with the same axial strain. The pore water pressure is always negative with different OCRs and unloading stress rates in compression and tension. The decreasing range increased with the increasing of OCR, and the influence rule of stress rate on the change range of pore water pressure is shear stress path related. The deformation modulus E100 increased with the increasing of OCR and stress rate; but the anisotropy of deformation modulus is becoming weaker as the increase of OCR under different stress rates.
Pages: 121-127
Year: 2013 Issue: z2
Journal: Rock and Soil Mechanics
Keyword: expansive clay; overconsolidation; stress rate; stress paths; deformation modulus;
Abstract: A total number of 21 consolidated undrained triaxial shear tests on Nanyang expansive clay have been performed by GDS stress path triaxial system. The specimens are prepared in kinds of 4 different overconsolidation ratios (OCR) for reduced triaxial compression (RTC) shear tests and 3 for reduced triaxial tension (RTT) shear tests, which all sheared at three different stress relief rates. The influences of OCR and stress rate on stress-strain relationship, pore water pressure, effective stress path and deformation modulus are investigated. The results show that the influences of OCR and stress rate on mechanical behavior of expansive clay in compression and tension are similar. As the increase of stress rate and OCR, the deviatoric stress in stress-strain curve increased monotonically to the maximum with the same axial strain. The pore water pressure is always negative with different OCRs and unloading stress rates in compression and tension. The decreasing range increased with the increasing of OCR, and the influence rule of stress rate on the change range of pore water pressure is shear stress path related. The deformation modulus E100 increased with the increasing of OCR and stress rate; but the anisotropy of deformation modulus is becoming weaker as the increase of OCR under different stress rates.
Related Articles