季节性冻土的水-热-力建模与数值分析

Modelling and Numerical Analysis of Moisture,Heat and Stress in Seasonal Frozen Soil

为了防治季节性冻土区由水-热-力相互作用引起的道路病害,对季节性冻土水-热-力耦合问题进行了研究。根据季节性冻土的特点,重点考虑了基质势和压力势与温度的关系,给出了季节性冻土水-热-力三场耦合的数学模型,并将耦合问题归结为求解一个非线性、非稳态温度场微分方程,含水量、应力及蠕变变形都可以在温度求解以后算出。详细推导了该方程的数值解法,包括有限元方程、时间域离散及迭代方法。最后对国道G109橡皮山段季节性冻土区公路路堤进行了数值模拟,对计算值与实测值做了对比。结果表明:采用水泥加固砂砾垫层的对比断面与采用砂砾垫层的原断面相比,其温度更低,含水量及预测的路面变形量更小。

In order to prevent the road diseases resulted by the interaction of moisture,heat and stress in seasonal frozen soil areas,the problem of coupled moisture,heat and stress in seasonal frozen soil was studied.According to the characteristics of seasonal frozen soil,mainly considering variation of the matrix potential and pressure potential with temperature,a model of coupled moisture,heat and stress in seasonal frozen soil was presented.The coupling problem was solved by solving a nonlinear differential equation of unsteady temperature field.Water content,stress and creep deformation could be calculated once the temperature field was determined.The numerical solution for the equation which included the establishment of finite element equations,discretization of the time domain and the iterative method was derived.The numerical simulation of the embankment of National Highway G109 near Xiangpi Mountain was carried out.The comparison of calculated value and measured value was made.The results show that the temperature,water content and predicted deformation of pavement in the highway section with grit cushion strengthened by cement are lower than that in the section with grit cushion unstrengthened by cement.