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基于格子Boltzmann方法土体CT扫描切片细观渗流场的数值模拟

ISSN号：1000-7598
期刊名称：《岩土力学》
时间：0
分类：TU411[建筑科学—岩土工程;建筑科学—土工工程]
作者机构：昆明理工大学建筑工程学院,云南昆明650500
相关基金：昆明理工大学人才培养基金资助（No.KKSY201306023;No.KKSY201306142）; 国家自然科学基金-云南联合基金重点项目（No.U1033601）

关键词：格子BOLTZMANN方法, 渗流场, 2D扫描切片, 数值模拟, lattice Boltzmann method, seepage field, 2D scanned slice, numerical simulation

中文摘要：

基于格子Boltzmann方法,采用D2Q9基本模型,上、下边界采用非平衡外推格式,左、右不透水边界及土颗粒采用反弹格式设置边界条件,对土体细观渗流场进行数值模拟。首先将试验测得物理单位的数据转化为格子单位,然后用Matlab编制程序,对CT扫描切片进行处理,生成土体细观的数据结构,最后把格子单位表示的结果再转为物理单位,分析了渗流流速的变化规律,得到了整体和局部渗流场的分布情况。分析结果表明：（1）孔道处的流速U随着入渗时间的延长而逐渐达到一个相对稳定值,进而得到流体从开始入渗至稳定状态经历的准确时间T;（2）平均渗流速度由入口处沿y轴负方向逐渐递减,且小于入口处的平均渗流流速;（3）渗流量主要受控于通道的连通性、孔隙大小,最大渗流速度集中在通道的窄孔道处,封闭的孔道和孔隙渗流速度为0。格子Boltzmann方法能有效地对CT扫描得到的2D切片进行数值模拟,可以定量、准确地研究真实土体渗流场的变化机制。

英文摘要：

Mesoscopic seepage field of real soil is simulated based on lattice Boltzmann method. In this simulation, the basic model D2Q9 is used; and the inlet and outlet boundaries are constructed by setting the non-equilibrium extrapolation format. The soil particles boundary as well as left and right waterproof boundaries are set by the bounce-back format. At first, the data denoted by physical units from experiments are transformed into lattice units. According to data structure generated by CT scanned slices, the corresponding calculation program is applied to simulate mesoscopic seepage field of real soil. Finally, the results of lattice units are transform into physical units once again. The variation of seepage velocity is analyzed; and the whole and partial distributions of seepage field are obtained. The results show that： 1） Seepage velocity U finally reaches a relatively stable figure in pore channels over time. Accurate time T is obtained from the beginning of seepage to the steady-state of seepage. 2） The average seepage velocity gradually decreases along with the negative direction of y axis from the inlet boundary; and it is less than the average seepage velocity in inlet boundary. 3） The quantity of seepage is dominated by the connectivity and pore size of channels. The maximum seepage velocity is concentrated in a narrow channel. The velocity in closed pore channel and pore is zero. Lattice Boltzmann method is effective in simulating two dimensional CT scanned slice and can be used to research the mechanism of real seepage field quantitatively and accurately.

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