冻土三轴蠕变非线性数学模型研究

Study of the Nonlinear Mathematical Model for Triaxial Creep of Frozen Soil

采用MTS-810液压伺服材料试验机,对人工配制的冻黏土试件进行了三轴蠕变试验,获得了冻黏土在复杂应力状态下的蠕变曲线.结果表明:冻土的蠕变变形具有较强的温度敏感性,温度越高,这种温度敏感性越强;相同温度下,荷载越大,变形越大.运用相关理论,推导了冻黏土在复杂应力状态下的三轴蠕变非线性数学模型,采用MATLAB软件的数据拟合功能得到了模型方程参数的数值,模型参数与温度之间存在密切关系,建立了二者之间的数学表达式.冻土三轴蠕变非线性数学模型的曲线与试验曲线拟合精度较高,建立的数学模型可以精确体现冻土的蠕变规律,能够为实际冻土工程的变形发展预测提供有效的理论指导.

The triaxial creep tests on laboratory-prepared frozen clay specimens are carried out with MTS-810 hydraulic servo material test machine,and then creep curves of frozen clay under complex stress state are obtained.The results show that the creep deformation of frozen soil has strong temperature sensitivity;the higher the temperature is,the stronger the temperature sensitivity is;at a same temperature,the larger the load is,the bigger the deformation is.Using relevant theory,the nonlinear mathematical model of triaxial creep of frozen clay under complex stress state is derived.Then equation's parameters of the model are obtained through fitting function of MATLAB software.There is a tight relationship between the model parameters and temperature.Thus a mathematical expression between the two is established.The fitting accuracies between the simulated curves and the experimental curves are high.The established mathematical model can accurately describe the creep law of frozen soil,and will provide effective theory for predicting the deformation in actual frozen soil engineering.