不同压实度花岗岩残积土的渗流模拟

以桂东南地区不同压实度的花岗岩残积土为研究对象,结合显微CT(micro computed tomography,微计算机断层扫描技术)扫描试验与Avizo软件中先进的数字图像处理技术提取孔隙网络模型.然后基于流体力学的传统方法(computational fluid dynamics,CFD),将孔隙结构的数字岩心模型导入Comsol进行微观尺度的渗流模拟,从微观角度研究水在不同压实度花岗岩残积土孔隙中的渗流特性,并与实测渗透率对比,检验数字岩心模型准确性、代表性.研究结果表明:花岗岩残积土渗流过程中,最大速度出现在连通性好的孔隙中心区域,且远超其他部位,沿着孔隙中心向外壁的方向,渗流速度逐渐减小;在连通性差的区域,流速近乎为0.随着压实度的增加,花岗岩残积土的孔隙连通性变差,各个截面上的孔隙结构发生变化,且各截面的平均渗流速度逐渐减小,这表明压实度对花岗岩残积土的渗流特性有重要影响.压实度为90％、100％、110％花岗岩残积土的平均渗透率模拟值分别是实测值0.9、1.35、0.77倍,该数字岩心模型能较准确地代表压实土体内部真实的孔隙渗流特征.

Seepage Simulation Of Granite Residual Soil With Different Compaction Degrees

Taking the granite residual soil with different compaction degrees in Southeast Guangxi as the research object, the pore space structure model was extracted by combining the micro-CT scanning test and the advanced digital image processing technology in the AVIZO software. Then, based on the traditional method of fluid mechanics (CFD), the model was imported into COMSOL to simulate the seepage at the micro-scale, and the seepage characteristics of water in the pores of granite residual soil with different compaction degrees were studied from the microscopic point of view, and compared with the measured permeability to test the pore Accuracy and representativeness of the spatial structure model. The research results show that during the seepage process of granite residual soil, the maximum velocity appears in the pore center area with good connectivity, and far exceeds other parts, along the direction of the pore center to the outer wall, the seepage velocity gradually decreases; in areas with poor connectivity, the flow rate is almost zero. As the degree of compaction increases, the pore connectivity of the granite residual soil deteriorates, the pore structure of each section changes, and the average seepage velocity of each section gradually decreases, which shows that the degree of compaction affects the seepage characteristics of the granite residual soil Have an important impact. The simulated values of average permeability of granite residual soil with compaction degrees of 90%, 100%, and 110% are 1.35, 0.9, and 0.77 times of the measured values, respectively. Pore seepage characteristics of compacted granite residual soils can be accurately modeled by the spatial structure model.