复杂应力路径下人工冻砂土非线性流变本构模型与应用研究

Nonlinear rheological constitutive model for frozen sand under complex stress paths and its engineering application

采用应力路径试验方法,模拟人工冻结法凿井井架地基施工变化过程,得到了冻砂土地基的变形规律:冻砂土轴向加载过程具有明显的剪胀性,且体积应变不能忽略。为了全面反映冻砂土在应力路径下的变形,以元件模型为基础,通过推导获得冻砂土非线性流变本构力学模型。利用有限元程序的二次开发技术,将该模型嵌入到FEPG有限元程序平台中,对冻砂土三轴蠕变试验和冻结法凿井井架地基受力过程进行了数值模拟。模型能够较好地反映冻砂土的变形随时间的变化规律,数值模拟、室内试验和实测值吻合较好,可为冻结法凿井设计和施工提供指导。

By use of the testing method of stress paths, the behavior of construction of artificial freezing derrick foundation was simulated. It was shown by the results of triaxial creep experiments that the frozen soil was obviously dilatancty, and its volume strain should not be neglected. To fully reflect the creep deformation laws of frozen soil under complex stress paths, a nonlinear rheological constitutive model of frozen soil was put forward by using the basic elements. And the model was embedded in FEPG finite element program on the basis of the secondary developing technique for FEM. It was shown by the results of numerical simulation for field measurement that the deformation properties of dilatancy and volume strain of frozen soil could be reflected by the nonlinear rheological constitutive model very well, and it agreed well with the field measurement data, which could be used as references for the calculation and construction of frozen projects.