Dong Liang, Tian Shuang, Yao Changrui, Han Xiao, Wang Ke
Railway Engineering Research Institute, China Academy of Railway Sciences Corporation Limited, Beijing 100081, China.
School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China.
Materials (Basel). 2022 Jul 23;15(15):5119. doi: 10.3390/ma15155119.
Using undrained triaxial shear tests, this study investigates the mechanical properties of fine-grained materials (silty clay and sand) which are extensively used for China's Qinghai-Tibet Railway (QTR) under different confining pressures () and freezing temperatures (). The results show that a reduction in causes an increase in the shear strength and elastic modulus of all the materials tested in the present study. In addition, the freezing of the silty clay has no significant effect on the type of soil behaviour (strain-hardening), whereas the freezing of the sand changes its strain-hardening behaviour to strain-softening. Supposing that the deviatoric stress-strain curves of the silty clay and sand can be divided into two segments due to a reverse bending point, it was assumed that the first segment follows a hyperbolic function. Meanwhile, the second segment is also a hyperbola, with the reverse bending point as the origin and the residual strength as the asymptote. Accordingly, a nonlinear relation constitutive model that considers and is derived. All model parameters are identified. The reasonability of the new model was verified using the test results of the materials. A comparison of the predicted and test results shows that this model can well simulate the deviatoric stress-strain response in the failure process of the tested materials. In particular, it can reflect the residual deviatoric stress after the materials' failure.
本研究采用不排水三轴剪切试验，对中国青藏铁路广泛使用的细粒材料（粉质黏土和砂土）在不同围压（）和冻结温度（）下的力学性能进行了研究。结果表明，围压的降低会导致本研究中所有测试材料的抗剪强度和弹性模量增加。此外，粉质黏土的冻结对土的性状类型（应变硬化）没有显著影响，而砂土的冻结则使其应变硬化性状转变为应变软化。假设粉质黏土和砂土的偏应力 - 应变曲线由于反向拐点可分为两段，则假定第一段遵循双曲线函数。同时，第二段也是双曲线，以反向拐点为原点，残余强度为渐近线。据此，推导了一个考虑和的非线性关系本构模型。确定了所有模型参数。利用材料的试验结果验证了新模型的合理性。预测结果与试验结果的比较表明，该模型能够很好地模拟测试材料破坏过程中的偏应力 - 应变响应。特别是，它能够反映材料破坏后的残余偏应力。
