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根据土壤冻结过程中水热迁移的基本方程，推导了土壤水热耦合方程，改进了冻结条件下土壤水热迁移问题的求解方法。用该模型模拟了室内土柱冻结试验，模拟结果与试验结果吻合较好，同时计算速度较快。根据地表能量平衡原理、微气象学理论，建立了冻结条件下土壤蒸发模型，将其作为土壤水热迁移的上边界条件，模拟了北京永乐店试验站冬小麦试区１９９５～１９９６年越冬期（１９９５．１２．０１～１９９６．０２．２９共３个月）土壤的冻融过程，模拟结果与实测值基本符合。在模拟过程中，采用有限差分法求解土壤水热运动方程，水、热方程的上边界分别为第二、三类边界。根据模拟结果，分析了越冬期土壤水热状况的变化规律
According to the basic equations of water and heat transfer during soil freezing process, the equation of soil water and heat coupling was derived and the method of solving soil water and heat transfer problem under freezing condition was improved. The model was used to simulate the indoor soil column freezing test. The simulation results agree well with the experimental results and the calculation speed is fast. According to the theory of surface energy balance and micrometeorology, the soil evaporation model under freezing condition was established as the upper boundary condition of soil water-heat migration. The winter wheat experiment period of 1995 to 1996 in Beijing Yongledian Experimental Station was simulated. .12.01 ~ 1996.02.29 a total of 3 months) soil freezing and thawing process, the simulation results and the measured value basically consistent. In the process of simulation, the finite difference method is used to solve the equation of soil hydrothermal movement. The upper boundary of water and heat equation are the second and the third boundary respectively. According to the simulation results, the change rule of soil water and heat during wintering period was analyzed