江夏法泗岩溶塌陷区冲孔桩施工引发岩溶塌陷的成因机理

依托武汉市岩溶地面塌陷区监测系统，开展江夏法泗冲孔桩施工过程裂隙岩溶含水层的水位、水压力和影响半径等关键参数的动态监测，研究施工过程岩溶含水层水压力的动态响应，探讨其诱发覆盖层突然塌陷的成因机理，结果表明:在第四系孔隙承压水含水层施工时，对该含水层的影响较大，但水位变幅相对较为平缓；在碳酸盐岩裂隙岩溶水含水层施工时，由于含水介质的不均一性，未揭穿岩溶通道时，对岩溶水的影响较小；当揭穿岩溶通道时，岩溶水水位可能产生突增，此时，诱发岩溶地面塌陷的风险加大。 

Mechanism of karst collapse caused by punching pile constructionin Jiangxia Fasi karst collapse area

In September 5th, 2014, the 8-1# pile foundation construction site of Wu-Jia expressway bridge in Jiangxia Fasi collapsed and had caused large-scale ground collapse, resulting in 19 different collapse pits. Buildings were damaged and the embankment of Jinshui river also collapsed, leading to the construction rig buried and the project forced to stop for 1 year. Based on the monitoring system of Wuhan karst collapse areas, the dynamic monitoring of groundwater in multiple aquifers and monitoring of vibration points at different parts were carried out during impact hollowing in the limestone fracture zone, from which key parameters such as water level, water pressure and influence radius of fractured karst aquifer were monitored during the punching pile construction process in Jiangxia Fasi. The response of the karst aquifer water pressure to the construction process was studied, as well as the mechanisms of construction-induced overburden collapses were researched. The study shows that the Quaternary confined aquifer is deeply influenced by inner construction activities, but the variation of the water level is relatively flat. In the fractured karst acquirers which are very heterogeneous, when the karst channels are not exposed on the surface, the construction has little effect on the karst water. However, if they are exposed, the karst water level may have a sudden increase which will increase the risk of karst collapse.