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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2015 Vol.16 No.3 P.171-181
Stress-dependent undrained shear behavior of remolded deep clay in East China
Abstract: Consolidated-isotropically undrained triaxial compression (CIUC) tests were performed on the reconstituted deep clay from a mine in East China. It was consolidated to maximum stresses in the range of 0.3–2.6 MPa. The test results show that the stress-strain-strength properties of the clay during undrained shear are significantly stress-dependent. In particular, in the case of high consolidation pressure, the post-peak drop in strength on stress-strain curves and shear plane in soil specimens are more evident, the peak stress ratio and the axial strain at which this ratio was reached are smaller, and the relationship between pore pressure and axial strain is also significantly different from that for the case of low consolidation pressure. The environmental scanning electron microscope observations and micro analysis lead to an understanding of the physical mechanisms underlying the above stress-dependent mechanical behavior. In addition, the CIUC behaviors of the studied clay are discussed in the context of critical state soil mechanics.
Key words: Deep clay, High pressure, Undrained triaxial compression, Stress-dependent behavior
创新点:1. 揭示重塑黏土的固结不排水剪切应力应变行为显著依赖固结应力水平的特点;2. 发现上述与应力水平相关的应力应变响应与黏土微观结构等密切相关。
方法:1. 开展重塑深部黏土不同压力水平下(表2)的三轴等向固结不排水剪切试验;2. 利用环境扫描电镜获得的颗粒结构特征,从微观结构角度揭示与压力相关的应力-应变、强度与孔隙水压响应的内在机理;3. 在临界土力学框架内讨论高压下重塑深部黏土的临界状态特征(图13和14)。
结论:1. 固结压力水平对重塑黏土的应力-应变-强度特性有显著影响;2. 随着固结压力的增加,软化现象和局部剪切带逐渐明显(图2和5),峰值应力以及相应轴向应变则不断减小(图8和9);3. 在大于2 MPa的高压固结不排水试验中,其孔隙水压/轴向应变曲线明显不同于常压(图3);4. 上述与压力相关的力学性质均与黏土微观结构相关(图6和12);5. 高压下黏土难以达到所谓的临界状态。
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DOI:
10.1631/jzus.A1400255
CLC number:
TU41
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On-line Access:
2024-08-27
Received:
2023-10-17
Revision Accepted:
2024-05-08
Crosschecked:
2015-02-26