基于CFP的岩溶管道流溶质运移数值模拟研究

A study of the solute transport model for karst conduits based on CFP

多重岩溶含水介质的复杂性导致岩溶地下水流动及溶质运移的数学模拟成为地下水研究难点之一。为了探讨岩溶多重含水介质中地下水流溶质运移特征,文章构建了管道流CFP水流模型和MT3DMS溶质运移三维耦合数值模型。在阐述管道流CFP和MT3DMS基本原理的基础上,通过建立水文地质概念模型算例(1个落水洞、4个直管道),探讨岩溶管道水流及溶质运移规律,分析讨论不同水文地质参数对浓度穿透曲线的影响。研究结果表明:管道流CFP模型能够刻画岩溶管道与基岩裂隙水流交换特征,MT3DMS模型能够模拟穿透曲线的拖尾现象,符合实际岩溶区特征。随着水力梯度、管道直径及管道渗透系数增大,孔隙度减小,浓度曲线峰值越大,峰值到达时间越快,浓度穿透曲线越对称。得出结论:耦合CFP水流模型和MT3DMS溶质运移模型能够刻画岩溶管道流溶质运移规律,为研究岩溶复杂介质污染物运移特征提供一种思路和途径。

To study the characteristics of solute transport for karst conduits,a coupling method of conduit flow process(CFP)and the modular three-dimentional transport model(MT3 DMS)is proposed.For the purpose of probing into the impacts of hydrogeological parameter on solute transport for karst conduits,based on analysis of the fundamentals of CFP and MT3 DMS,the authors established the concept model with one sink hole and four conduits.The results of the coupling model show that the CFP model permits the exchange of groundwater between matrix and pipe,and the tailing feature of the breakthrough curve for karst conduits is well depicted.With the decreasing effect from porosity and the increasing effect from pipe diameter and the increasing pipe conductance and hydraulic gradient,the curve peak became larger,and the time to reach the peak becomes quicker and the symmetry of the curve is more apparent.Thus,the coupling model of CFP and MT3 DMS can depict the characteristics of solute transport for karst conduits,but cannot simulate the multi-peak curve.How to generalize the physical characteristics of karst conduits is a way to resolve the multi-peak issues.