【摘要】 考虑热源作用下非饱和土体水热耦合作用机制,基于格子Boltzmann方法,采用双分布函数分别描述温度场及水分场的演化过程,建立了相应的水热耦合模型。同时,编制了计算程序,并结合半无限空间的水热耦合算例,验证了该计算模型的正确性。最后考虑水热耦合作用模式、热源温度以及土体孔隙率等因素的影响,讨论了非饱和土体温度场及水分场的演化规律。研究结果表明:传统的单向耦合模式无法表征水分迁移对土体导热特性的影响,从而导致温度场的演化规律有所偏差,而所提出的双向耦合模式更具合理性。在恒温热源作用下,不同热源温度对土体温度场及水分场的演化均会产生较大影响,且在非饱和土体温度升高速率较快的位置,体积含水率也相应的变化较快。在相同热源作用下,当初始体积含水率一定时,孔隙率较小的土体,温度升高速度较快,但总体差别不大,从而使得体积含水率分布也较为接近。更多还原

【Abstract】 By considering the moisture-heat coupling mechanism of unsaturated soil under heat source, the double distribution functions are employed to describe the evolution of temperature field and moisture field respectively, and the coupled moisture-heat model is established based on the lattice Boltzmann method. Meanwhile, the corresponding program is compiled to verify the proposed model, using an example of moisture-heat coupling problem in the semi-infinite space. Finally, the evolution of temperature field and moisture field in unsaturated soil are discussed considering the effects of moisture-heat coupling mode, heat source temperature, and soil porosity. The results show that the traditional one-way coupling mode could not characterize the influence of moisture migration on the thermal conductivity of soil, which leads to deviation of temperature field. The proposed two-way coupling mode is more reasonable. The evolution of temperature field and moisture field are greatly influenced by the heat source temperature, and the volume moisture content also changes rapidly at locations where the temperature of unsaturated soil rises fast. Under the same heat source, when the initial volume moisture content is constant, the temperature increases faster for the soil with lower porosity, but the overall difference is not significant, which makes the distribution of volume moisture content very close.更多还原