基于颗粒流理论和流固耦合效应,利用PFC^3D程序内置的FISH语言编程,建立基土-滤层渗流模型,针对具有不同级配特征的管涌型土(连续级配、间断级配),分别进行不同层间系数情况下的系列数值模拟试验,分析渗滤系统中基土、滤层及两者界面处的孔隙率、渗透率、基土流失百分量等参数随渗流作用时间的演化过程,并分析和评估渗滤系统的保土性和透水性。结果显示对应于不同级配特征的管涌土,其基土-滤层渗滤系统的层间系数值(D₁₅/d_85*)都存在一个最优范围,当层间系数值在该范围内时,由基土-滤层构成的渗滤系统沿渗流方向的透水性逐渐增大,表现出良好的保土性与透水性;连续级配特征的基土自反滤能力较强,其最优层间系数值的范围较宽,而间断级配特征的基土最优层间系数值的范围较窄。

Seepage model of base soil-filter system which takes into account the coupling of solid and fluid was established in association with the built-in FISH programming language of PFC^3D software. Piping-typed soils of continuous gradation and discontinuous gradation were simulated in the presence of various coefficients between layers. The variations of porosity, permeability, loss fraction of base soil filter material, as well as the interface between the two with seepage duration were traced and recorded, and then the water-retaining performance and permeability of the base soil-filter system were evaluated. Results show that there is an optimal range for the coefficient between layers (D₁₅/d_85*) of different piping-typed soils in the base soil-filter system. When values of the coefficient between layers are in the range , permeability of the infiltration system gradually increases along seepage direction, displaying good performances of conserving soil and permeability. Furthermore, base soil of continuous gradation has better filtration ability and a wide range of the optimal coefficient between layers, whereas the optimal range for soil of discontinuous gradation is narrow.