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摘要: 黄土边坡开挖过程中常遇到边坡发生变形甚至破坏的情况，不同的开挖速率导致边坡的变形特征也不相同。通过饱和黄土的卸载三轴试验，研究固结围压及卸载速率对卸载状态下饱和黄土的应力-应变特性、孔隙水压力的发展及应力路径的影响。试验表明，固结围压越大，土体破坏所需的偏应力越大，抗剪强度越大；卸载速率越大，对应的偏应力峰值越大，抗剪强度越大。卸载速率相同时，土体卸载初期的超静孔压为负值，增大至正值后孔压的增长速率在其增大过程中逐渐减小；固结围压越大，土样剪切过程中对应的孔隙水压力越大。卸载三轴试验中，土体均表现为应变软化的特性；饱和黄土破坏时的应变均为1%~3%，且固结围压越高，破坏时的应变越小。固结围压相同时，卸载速率越大，孔压增长速率越快，但孔隙水压力值越小。Abstract: The deformation and destruction of loess slopes have become a common phenomenon in the excavation process. Different excavation rates will lead to different slope deformation characteristics. The stress-strain characteristics, the development of pore pressure and the stress path of saturated loess under unloading conditions are studied based on the unloading triaxial tests. The research results indicate that the higher consolidation pressure and the larger unload rate will produce larger deviatoric stress and greater shear strength. When the unloading rate is constant, the value of pore pressure at the initial stage of soil unloading is negative. As it increases to a positive value, the growth rate of the pore pressure begins to decrease during the subsequent growing process. The higher consolidation pressure produces the larger corresponding pore water pressure. In the unloading triaxial test, the loess is characterized by strain softening and the shear failure strain ranges from 1% to 3%. In addition, the higher consolidation pressure may result in the smaller shear failure strain. When the consolidation pressure is constant, the larger unload rates will produce the larger growth rates of pore water pressure and the smaller values of pore water pressure.
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Key words:
- saturated loess /
- unloading triaxial tests /
- consolidation pressure /
- unloading rate
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