Evolution of Shear-Zone Structure in Undrained Ring-Shear Tests
Evolution of Shear-Zone Structure in Undrained Ring-Shear Tests
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DOI：
10.1007/s10346-004-0001-9
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发表时间：
2004-07-01
期刊：
影响因子：
6.7
通讯作者：
Wang, Gonghui
中科院分区：
文献类型：
--
作者：
Agung, Muhammad Wafid;Sassa, Kyoji;Wang, Gonghui
利用环剪仪对细粒硅砂进行了不排水单调扭矩控制试验，研究了颗粒材料的剪切变形过程。剪切带结构在不排水剪切试验的各个阶段，观察在一系列的试验中，实验终止于不同的剪切位移。对于“未受干扰”的样品，剪切带只在破坏后阶段发展，其厚度随着剪切的进行而增加。剪切面起初呈起伏状、不对称结构，后来逐渐变得光滑，并与剪切方向平行。在此过程中，产生了孔隙水压力，有效内摩擦角相应减小。剪切带一般可分为三个部分：压实核心区、核心区上方的邻近区和核心区下方的邻近区。对剪切带样品的粒度分析表明，颗粒破碎发生在每个阶段和不同的剪切阶段的颗粒破碎的程度不同。一个有趣的现象发生在稳态变形过程中，粗颗粒和细颗粒在剪切区分离运动和平行取向结构的发展。这些结果有助于理解散体材料的渐进破坏机理，也有助于长跳动快速滑坡的研究。
Undrained monotonic torque-controlled tests were conducted on fine-grained silica sand to study the shear-deformation process in granular materials by using a ring-shear apparatus. Shear-zone structures at various stages in the undrained shear tests were observed during a series of tests in which the experiments were terminated at different shear displacement. For "undisturbed" samples, the shear zone was only developed during the post-failure stage and its thickness increased with progressed shearing. First the shear surfaces had undulating and asymmetric structures; later they gradually became smooth and parallel to the shearing direction. During this process, pore water pressure was generated, and the effective friction angle decreased correspondingly. Generally, the shear zone could be divided into three parts: the compacted core, the adjacent zone above the core, and the adjacent zone below the core. Grain-size analysis on the sample from the shear zone revealed that grain crushing occurred during each stage and the extent of grain crushing differed for different shear stages. An interesting phenomenon occurred during the steady-state deformation where the coarse and fine particles within the shear zone segregated during motions and a parallel orientation structure developed. These results are helpful for understanding the mechanism of progressive failure in granular material as well as the rapid landslide with long runout study.