基于格子Boltzmann方法的非饱和土体导热系数研究

RESEARCH ON THERMAL CONDUCTIVITY OF UNSATURATED SOIL BASED ON LATTICE BOLTZMANN METHOD

以非饱和土体为研究对象,通过四参数随机生长法(QSGS)对土体的微观结构重构。根据土体各相及相间的热传导方程,建立求解非饱和土体有效导热系数的数学模型。基于格子Boltzmann方法的D2Q4模型对该模型进行求解。研究结果表明:土体的有效导热系数随饱和度的增加而增大,且冻土的变化幅度远大于未冻土。土体的有效导热系数随孔隙率的增加而减小,孔隙率较小时其下降速率较快。在土颗粒分布均匀、各向同性且孔隙率相等的情况下,土颗粒大小对土体有效导热系数的影响不显著。当片状土颗粒排列平行于传热方向时,其有效导热系数要大于排列垂直于传热方向的土体。

The microstructure of unsaturated soil is reconstructed by quartet structure generation set(QSGS).According to the heat conduction equation of each phase and each phase interface,a mathematical model for solving the effective thermal conductivity of unsaturated soil is established.The D2Q4 model based on lattice Boltzmann method is used to solve the model.The results show that the effective thermal conductivity increases with the increasing of saturation,the variation amplitude of frozen soil is much larger than that of unfrozen one.The effective thermal conductivity decreases with the increasing of porosity,the decrease rate is faster when porosity is small.When the porosity is equal,the particle distribution is uniform and isotropic,soil particle size has little influence on the effective thermal conductivity.When the flaky particles are arranged parallel to the direction of heat transfer,its effective thermal conductivity is greater than that arranged perpendicular to the direction of heat transfer.