冻土的有限变形本构关系的实验研究

An Experimental Study on Finite Strain Constitutive Relations of Frozen Soil

根据有限变形理论,给出了冻土三轴蠕变实验数据处理时所需Green应变和Kirchhoff应力的计算公式,并根据冻土三轴蠕变实验结果给出冻土的有限变形本构关系及其蠕变参数。通过对冻土的实验数据对比分析可知:在相同试验条件下,应变较小时,小应变ε1 和Green应变Ez的数值几乎相等,随着应变的增加,两种表征方式的计算结果差别越来越大,可见对于冻土如果不考虑试件变形前后长度的变化,计算得出的应变偏离实际变形情况较大,因此冻土材料的本构关系采用有限变形表征更确切。根据冻土的有限变形本构关系计算得到的冻结壁内侧最大径向位移更接近实测结果,因此冻结壁设计计算依据冻土的有限变形本构关系更为合理。对今后冻结工程的设计具有参考价值。

Based on the finite strain description of deformation, the formulas of Green strain and Kirchhoff stress were put forward for applying to the triaxial creep experimentation of frozen soil. The finite strain constitutive relations of frozen soil were deduced and the parameters of creep in the equations were fitted with the results of triaxial creep experimentation of frozen soil. Under the same conditions, the small strain ε\-1 is almost equal to Green strain E\-z when strain is small. Along with strain increment, the difference is more and more remarkable between small strain ε\-1 and Green strain E\-z. If we take no account of the length variation of the frozen soil specimen, the numerical values of strain will deviate from actual deformation situation. Therefore the finite strain constitutive relations are more accurate for frozen soil. The results of tests have also shown that the finite strain constitutive relations of frozen soil are more reasonable for design and deformation evaluation of the ice wall. The remarks above could provide the reference for design of the ice wall in the deep strata for the future.