岩溶演化过程中含水介质的时空变化特征研究

Research on spatio-temporal change characteristics of karst water-bearing medium in evolution process

根据碳酸盐岩溶蚀机理,对裂隙溶蚀过程进行合理简化和假设。在此基础上,建立了耦合裂隙渗流模型和隙面化学动力学模型的裂隙溶蚀扩展模型,据此对不同条件下单裂隙扩展的特征和规律进行分析研究。结果表明:岩溶演化受裂隙几何形态和水动力条件的共同影响,岩体裂隙较闭合或地下水水流滞缓时,岩溶均不易发育;在岩溶发育演化过程中,含水介质的整体渗透性显著增强,水流状态由层流变为紊流,流量呈级数增加,而溶蚀速率将趋于恒定,水头坡降趋于平缓。

The dissolving process of karst fracture is theoretically simplified according to the dissolution mecha- nism of carbonate rock. A model coupled with the fissure surface chemical-kinetic and fissure seepage is set up, then the single-fissure widening features and laws under different boundary conditions are analyzed and studied. The results show that the dissolution widening rate is determined by the hydraulic gradient and initial width of fracture. If either the rock fracture is closed or the groundwater flow is slow, karst evolution is diffi- cult. During the karst development and evolution process, the permeability of water-bearing medium signifi- cantly enhanced, the flow status change from laminar to turbulent, and the flow rate increase exponentially, while the dissolution rate is almost invariable, and the gradient of water table tends to slow.