基于QSGS法3D重构土体渗流场的LBM数值模拟  

LBM Numerical Simulation of Seepage Field of 3D Reconstructed Soil Based on QSGS Method

作　　者：阙云[1] 邱婷 蔡沛辰 马宏岩[1] 谢秀栋[1] 薛斌 QUE Yun;QIU Ting;CAI Peichen;MA Hongyan;XIE Xiudong;XUE Bin(School of Civil Engineering,Fuzhou University,Fuzhou 350108,China)

机构地区：[1]福州大学土木工程学院,福建福州350108

出　　处：《湖南大学学报（自然科学版）》2023年第9期119-130,共12页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(41772297)。

摘　　要：基于四参数随机生长法(QSGS)以及改进QSGS方法等效重构三维(3D)各向同性/各向异性土体内部孔隙结构,结合格子玻尔兹曼方法(LBM),采用MATLAB自编程序进行细观渗流场数值模拟,分析不同孔隙参数及模型各向异性等因素对渗流特性的影响规律.结果表明:3D模型尺寸100×100×100格点时,连通孔隙率nc达到最大增幅19.23%.流体易在连通性好、孔喉直径大的部位形成主渗流通道,且存在“指进效应”,流体越靠近孔道中轴线流速越快.3D重构土体的计算渗透率k随模型孔隙率n增大而增大,随土颗粒尺寸减小而减小,当分布概率pc=0~0.05(大、中颗粒)时渗透率显著降低,降低幅度达42.86%.考虑各向异性的重构模型出口边界渗流速度波动幅度较大、变化趋势规律性不明显,且流线分布稀疏、相互交错、主渗流通道不明显.该研究能揭示流体在3D土体孔隙结构中的流动规律,并为3D土体重构和细观渗流模拟研究方法提供借鉴.The quartet structure generation set(QSGS),as well as improved QSGS,were used to equivalently reconstruct the three-dimension(3D)isotropy and anisotropy pore structure of the real soil.Combined with the lattice Boltzmann method(LBM),the numerical simulation of the seepage field employing the MATLAB automatic program was carried out to explore the influence of different pore parameters and model anisotropy on seepage characteristics.The results showed that when the mesh size of the 3D model was 100×100×100,the maximum increase of pore connectivity rate nc reached 19.23%.The fluid preferred to form the main seepage channel in the position with good connectivity and large pore throat diameter,and there was a“finger-in”effect.The closer the fluid was to the axis of the channel,the greater the flow velocity was.The calculated permeability k of 3D reconstructed soil increased with the increase of model porosity n and decreased with the decrease of soil particle size.When the distribution probability Pc was 0~0.05,the permeability k decreased significantly,and the reduction was 42.86%.The seepage velocity at the outlet boundary of the reconstructed model considering anisotropy fluctuated greatly and irregularly.The streamline distribution streamline sparse and interlaced,with no prominent main seepage channel.This study can better reveal the flow law of fluid in the 3D pore structure and provide some references for the research methods of 3D soil reconstruction and meso-seepage simulation.

关 键 词：格子玻尔兹曼 四参数随机生长法 细观渗流 各向异性 计算渗透率 

分 类 号：TU42[建筑科学—岩土工程] O357.3[建筑科学—土工工程]