基于邓肯-张的冻结粉质粘土本构模型试验研究

为研究冻结粉质粘土强度和变形特性，以沈阳地铁DK11+395联络通道处人工冻结粉质粘土为研究对象，通过冻土三轴剪切试验，研究了不同试验条件下冻结粉质粘土的强度和变形特性。试验结果表明：围压、温度和试件初始含水量是影响冻结粉质粘土强度和变形的主要因素。冻结粉质粘土偏应力-应变曲线呈应变硬化型，其破坏强度和切线弹性模量随围压和试件初始含水量的增加而增大，随温度的升高而减小，破坏偏应力比Rf取值在0.79~0.96之间。基于试验数据建立了以上述三因素为影响因子的冻结粉质粘土Duncan-Chang模型。通过回归分析，建立了模型参数a和b与围压、初始含水量和温度之间的线性回归公式。将依据模型计算的偏应力-应变曲线与对比试验曲线相比较，发现两者具有较好的吻合程度，说明建立的模型能够准确反映围压、初始含水量和温度等条件对冻结粉质粘土强度和变形的影响规律。上述研究成果为冻结粉质粘土强度和变形特性的研究提供了参考，为人工冻结法施工提供了指导，具有重要的理论意义和工程应用价值。

The EXPERIMENTAL RESEARCH ON CONSTITUTIVE RELATIONSHIP OF FROZEN SILTY CLAY BASING ON THE DUNCAN-ZHANG MODEL

Abstract In order to research the strength and deformation characteristics of artificial freezing frozen silty clay, the soil samples which carried from the construction of connecting passages in DK11+395 of Shenyang subway are taken as the research sample. The strength and deformation characteristics of frozen silty clay are studied through triaxial shear test for frozen soil under different confining pressures, different temperatures and different initial moisture contents. The results indicate that confining pressures, temperatures and initial moisture contents are the most important influence factors for the strength and deformation characteristics. The deviatoric stress versus strain curves of frozen silty clay is hardening. The failure strength (σf) and elasticity modulus (Et) are increasing with confining pressures (σ3c) and initial moisture contents (ω), but decreasing with the temperatures (T). The value of deviator stress ratios are between 0.79~0.96. The Duncan-Chang Model which considered the confining pressures, temperatures and initial moisture contents are established based on the triaxial shear test data. The regress equations between the model’s parameter a, b and σ3c，T and ω are built by using the regression analysis. The calculated deviatoric stress versus strain curves which obtained from the model and the contrast tests are compared. The comparison results show that the calculated results fit well with the test results. The results also show that the model which has been established is efficacious. It can reflect the strength and deformation characteristics of frozen silty clay in different confining pressures, different temperatures and different initial moisture contents. The research results provide a reference to the study of the deformation and strength properties of frozen silty clay and the guidance for the artificial freezing construction. It has not only important theory value, but also has important application value of engineering.