裂隙岩溶含水系统溢流泉演化过程的数值模拟

本文利用非连续裂隙网络介质模型,耦合水动力条件和碳酸盐溶蚀动力条件,建立岩溶含水系统演化的数学模型,并用数值法进行模拟分析。在已建数值模型基础上,构造了两组实例模型(降水入渗补给的裂隙岩溶含水系统和河流补给的裂隙岩溶含水系统)来研究裂隙岩溶系统中溢流泉早期演化过程。模拟发现,裂隙岩溶含水系统演化过程中,裂隙不断被溶蚀拓宽,致使系统中潜水位不断下降,许多小泉被疏干;同时不同裂隙之间存在溶蚀差异,在潜水位及优势通道附近的裂隙溶蚀速度快,而其它位置则相对慢得多,差异溶蚀促使系统形成优势溶管,优势溶管逐渐袭夺水流,形成大泉。另外对比两模型发现,降水入渗为主要补给源的裂隙岩溶含水系统,泉管道从汇向源发育;而河流入渗为主要补给源的裂隙岩溶含水系统,泉管道则由源向汇发育。 

Numerical simulation for the evolution of the overflow spring in fracture-karst aquifer system

Based on discontinuous fracture network medium model, coupled hydrodynamic conditions and the dynamic conditions of carbonate dissolution, this paper established a mathematical model and take numerical method to simulate and analyze the evolution of fracture-karst aquifer system. On the basis of established numerical model, two sets of instance model are constructed(one fracture-karst aquifer system recharged by precipitation and the other one recharged by river) to study the early evolution of overflow spring in the fracture-karst system. It is found that with the evolution of fracture-karst aquifer system, the fractures are constantly corroded and widened, which lead to water table declines and many springs being drained out. Moreover, since the variance dissolution, corrosions are quicker at the water table and in the vicinity of the dominant fracture, while the other location is relatively slow, and a karst dominant tube is gradually formed which captures most of the water in the system and develops large spring. Comparing the two instance models, it is also found that in rainfall infiltration recharged system, the springs develop from the sink to the source; while in river infiltration recharged system, the springs develop from the source to the sink.