地铁建设对岩溶水渗流场影响的修复效果模拟

地铁工程因穿越岩溶含水层，易引起地下水渗流场发生变化，从而诱发工程及地质问题，为保护地下水环境，迫切需要一种简易且安全的疏导方案。为探讨地铁建设对地下水渗流场的影响，在总结研究区岩性结构及其水文地质特征的基础上，采用数值模拟方法模拟地铁车站建设前后及增加导流措施后地下水渗流场的变化，分析不同地质条件下地铁建设对地下水渗流场的影响并验证导流措施的修复能力。结果表明：研究区地铁车站地下水渗流结构可划分为土层夹卵砾石-岩浆岩孔隙-裂隙渗流双层结构(车站A)、土层夹卵砾石-灰岩孔隙-岩溶渗流结构(车站B)、土层夹碎石厚层单层孔隙渗流结构(车站C)3大类，地铁基坑建设对周边原有渗流场水动力条件的影响程度与地层结构密切相关。地铁车站的建设导致迎水面水位上升，背水面水位下降，车站A、车站B和车站C迎水面水位最大壅高分别为0.40、0.32和0.62 m;对地下水渗流场的影响范围与地质条件、车站数量以及车站建设方向与水流方向的夹角密切相关，总体上迎水面影响范围大于背水面。导流措施能最大程度恢复地下水渗流场，各车站地下水回落后的水位与天然水位的欧式贴近度均大于0.98。但导流措施布设的数量与位置同时受水...

Simulation of remediation effect of karst water seepage field influenced by subway construction

When the subway construction runs through a karst aquifer, it always causes the change of groundwater seepage field, resulting in engineering and geological problems. In order to protect the groundwater environment, a simple and safe diversion scheme is urgently needed. Based on the summary of the lithological structure and hydrogeological characteristics of the area studied, a numerical simulation method is used to simulate the change of groundwater seepage field before and after the construction of the subway stations, as well as after the implementation of diversion measures, so as to investigate the influence of subway construction on groundwater seepage field under different hydrogeological conditions and to testify the remediation effect of diversion measures. The results show that the subway station structure can be divided into three categories, namely, the double-layer seepage structure with gravel-magmatic rock pores-fissures in the soil layer(station A), the seepage structure with gravel-limestone pores-karst in the soil layer(station B) and the single-layer pore seepage structure with thick gravel in the soil layer(station C). The influence of subway foundation pit construction on the hydrodynamic conditions of the surrounding original seepage field is closely related to stratum structure. The construction of the subway station leads to the rising of the water level on the upstream face and the falling of the water level on the downstream face, the maximum backwater height of the upstream face of station A, station B and station C is 0.40, 0.32 and 0.62 m, respectively. The influence range of groundwater flow field is closely related to geological conditions, the number of stations and the angle between the directions of station construction and water flow. Generally speaking, the influence range of the upstream face is larger than that of the downstream face. Diversion measures can restore the groundwater seepage field to the greatest extent, and the Euclidean closeness between the fallen-back water level and the natural water level at each station is greater than 0.98. However, the number and location of diversion measures are affected by multiple factors such as water flow angle, geological structure, hydrodynamic conditions and so on, which should be considered according to the actual situation. The research results can provide a scientific reference for the harmonious coexistence of subway engineering construction and groundwater environmental protection.