不同离散化方法在正冻土水热耦合模型中的应用

DIFFERENT DISCRETIZATION METHOD USING IN COUPLED WATER AND HEAT TRANSPORT MODE FOR SOIL UNDER FREEZING CONDITIONS

为了研究土体冻结过程中温度传导与水分迁移的变化,在不饱和土理查德斯方程的基础上考虑相变作用建立了一维土体冻结过程的水热耦合模型。分别应用有限差分与有限元方法对模型进行离散化,得到两种方法各自的数值计算程序。同时对土体室内单向冻结实验进行模拟,将两种数值方法得到的土体冻结深度、冻结速率与温度变化分别与实验结果进行对比。结果表明:对于一维冻结问题,有限差分模拟更接近实验结果,有限元模拟具有更高的计算稳定性。

A coupled water and heat transport mode is established, based on the Richards equation to study the water flow and heat transport in soil during a freezing process. Both the finite difference and finite element method are used in the discretization respectively. Two different computer programs are written and employed to simulate an indoor unidirectional frozen test. The freezing depth, freezing rate and temperature variation are compared among the real test, the finite difference calculation model simulation and the finite element calculation model simulation. The result shows that： the finite difference method has a better performance in freezing depth simulation and the finite element method has a better performance in one-dimensional freezing stability simulation.