模拟船闸底板减压井的等效表孔法

Equivalent surface hole method for simulating pressure-reducing wells at bottom of ship lock

根据流量等效原则及阻力系数法,提出一种“以表孔代井”的实用简化方法,将地基上三维减压井等效为同位置二维表面孔,并给出表孔半径换算估算式。经验证,该方法在列井、群井问题中等效性良好。依托双线船闸闸室,通过渗流势分布、渗流量分配和扬压力变化规律的对比分析,评价等效表孔法计算精度。结果表明,该方法可有效减少模型单元数与节点数,极大地节省计算资源。等效表孔与减压井横剖断面渗流势相同,各部位水头线几乎重叠,出流量横向分布一致,等效模型与原模型右线出流总流量相对误差仅为1.7%,平均扬压力相对误差5.4%。建议等效表孔率不宜小于10%,等效表孔率大于50%时,扬压力基本等同于完全透水情况,可直接按闸室完全透水进行渗流分析。

According to the principle of flow equivalence and the method of resistance coefficient,a practical simplification method of“replacing well with surface hole”is proposed.This method simplifies three-dimensional pressure-reducing wells as two-dimensional surface holes at the same position,and the calculation formula of surface hole radius is given in this paper.It is proved that the method has a promising application in terms of row wells and group wells.Based on the project of double line lock chamber,the calculation accuracy of the practical simplification method is evaluated by the comparative analysis of seepage potential distribution,seepage flow distribution and lifting pressure variation.The results show that the simplified method can effectively reduce the number of model elements and nodes,and greatly save computing resources in numerical simulations(FEM).Moreover,the outcomes illustrate that the seepage potential and the lateral distribution of discharge flow of equivalent surface hole is the same as those of relief well,and the top lines of each part in those two models are almost overlapped.The relative error between the total discharge flow of equivalent model and the right line of original model is only 1.7%,the relative error of the average uplift pressure is 5.4%.It is suggested that the equivalent orifice rate should not be less than 10%,the seepage analysis can be carried out directly according to the fully permeable of the lock chamber when the equivalent orifice rate is greater than 50%owing to the fact that the lifting pressure is basically equivalent to the situation of complete permeability.