论文标题
基于X射线计算机断层扫描的不饱和砂中循环水保留行为的多相晶格玻尔兹曼建模
Multiphase lattice Boltzmann modeling of cyclic water retention behavior in unsaturated sand based on X-ray Computed Tomography
论文作者
论文摘要
水保留曲线（WRC）定义了矩阵吸力与饱和度之间的关系，是确定不饱和土壤的水力机械行为的关键功能。我们研究了使用计算机断层扫描（CT）实验和多相晶格Boltzmann方法（LBM）的颗粒土壤保留行为的可能起源。我们在汉堡砂上进行了CT实验，以获得其WRC，然后基于CT晶粒骨架进行LBM模拟。多相LBM模拟捕获了CT实验中观察到的WRC的磁滞和孔尺度行为。使用LBM，我们观察到气体簇的空间分布和形态在排水和吸收路径之间有所不同，并且是滞后的潜在来源。在排水期间，气体簇聚集在晶粒表面。当气体簇通过小孔口进入时，局部吸力会增加，而当气体簇通过大孔口进入时，则局部吸力会减少。而在吸收期间，气体簇分散在液体中；局部吸力均匀下降。在排水期间，首先空的大毛孔，小毛孔在吸收期间首先充满。基于孔隙的WRC表明，孔径的增加会导致排水和吸收期间吸力的减少，并且滞后增加。
The water retention curve (WRC) defines the relationship between matric suction and saturation and is a key function for determining the hydro-mechanical behavior of unsaturated soils. We investigate possible microscopic origins of the water retention behavior of granular soils using both Computed Tomography (CT) experiment and multiphase lattice Boltzmann Method (LBM). We conduct a CT experiment on Hamburg sand to obtain its WRC and then run LBM simulations based on the CT grain skeleton. The multiphase LBM simulations capture the hysteresis and pore-scale behaviors of WRC observed in the CT experiment. Using LBM, we observe that the spatial distribution and morphology of gas clusters varies between drainage and imbibition paths and is the underlying source of the hysteresis. During drainage, gas clusters congregate at the grain surface; the local suction increases when gas clusters enter through small pore openings and decreases when gas clusters enter through large pore openings. Whereas, during imbibition, gas clusters disperse in the liquid; the local suction decreases uniformly. Large pores empty first during drainage and small pores fill first during imbibition. The pore-based WRC shows that an increase in pore size causes a decrease in suction during drainage and imbibition, and an increase in hysteresis.
