基于LBM的2D/3D原状花岗岩残积土细观渗流模拟

Simulation of 2D/3D Mesoscopic Seepage in Undisturbed Granite Residual Soils Based on the LBM

为刻画原状土体内部孔隙细观渗流特征,选取东南沿海地区某地原状花岗岩残积土作为研究对象,基于计算机断层扫描(CT)和图像处理技术对2D/3D原状土体模型进行重构,并结合格子Boltzmann方法(LBM),通过自编程序模拟土体孔隙内水分渗流及分布情况.结果表明:孤立孔隙对渗流结果影响甚微,仅个别连通性好、孔径大且笔直的大孔隙会成为优势通道并产生优先流;渗流从开始至稳定过程中,最大流速主要出现在孔隙通道由宽变窄处,孔隙结构形态对渗流的影响较孔隙占比更为显著.基于工业CT扫描技术和LBM能较好刻画真实土体孔隙渗流特征,2D模型可更直观表现大孔隙优先流现象,适用于定性研究;3D模型更接近实际情况,可精确计算土体渗透率,适用于定量研究.

In order to characterize the mesoscopic seepage of pore spaces within undisturbed granite residual soil(UGRS).The 2D/3D pore models of UGRS were reconstructed using computed tomography(CT)scanning and image processing technology.The lattice Boltzmann method(LBM)was employed to simulate the seepage displacement process and water distribution in UGRS pores through programming.Results indicate that isolated pores have minimal impact on seepage outcomes.Only a few large,straight pores with good connectivity become dominant channels,generating preferential flow.Throughout the seepage process,the maximum velocity in the dominant passage shifts from the inlet to the middle and then to the outlet region.The influence of pore structure characteristics on seepage is more significant than pore proportion.Using industrial CT scanning technology and LBM provides a better description of real soil pore flow.The 2D model intuitively illustrates the preferential flow phenomenon of macropores,suitable for qualitative research.The 3D model,closer to reality,accurately calculates soil permeability,making it suitable for quantitative research.