基于并行FDM模型和流网计算的土体渗流

Analysis on Safety Factors of Soil Seepage Based on FDM and Flow Net Calculation

摘要:

常规二维稳态流网计算得到的渗流安全系数接近于临界值，将导致设计过程中采取超量设计的方法对结构进行冗余防护。因此，提出了基于有限差分法（FDM）模型对流网进行二次修正的方法，将计算截面离散化，利用FDM步长单元小、迭代计算次数多的优势获得新的等势线和流线，并用修正后的水头梯度和渗流路径重新计算渗流量和安全系数。结果表明：基于FDM模型修正的每日渗流量为2.77 m³/m，与二维稳态流网的计算值3.29 m³/m基本一致，但经FDM模型修正后的渗流安全系数为2.7，远大于二维稳态流网的计算值1.6。由此说明，经FDM模型修正后的流网计算结果精度较高，结构安全性更可靠。

Abstract:

The seepage safety factor calculated by the conventional two-dimensional steady flow net is close to the critical value, which will lead to the redundant protection of the structure by over-design method in the design. Therefore, a method based on the finite difference method (FDM) model is proposed for the double-modified flow net. The cross section is discretized, and the new equipotential lines and streamlines are obtained by using the advantages of small step unit and many iterations of FDM. The seepage rate and safety factor are recalculated by the modified head gradient and seepage path. The results show that the modified seepage based on the FDM model is 2.77 m³/d/m, which is basically consistent with the calculated value 3.29 m³/d/m of the two-dimensional steady flow net. However, the seepage safety factor of the modified FDM model is 2.7, which is much higher than the calculated value 1.6 of the two-dimensional steady flow net. It is explained that the calculation result of the flow net modified by FDM has the higher precision and the structure safety is more reliable.