Mechanism mode and prevention and control measures of karst collapses induced by foundation pit excavation

With the rapid development of urbanization construction in China and the continuous growth of the real estate industry, the issue of karst collapse induced by deep foundation pit excavation in high-rise building construction has become increasingly prominent. This paper studies the impact of foundation pit excavation on groundwater and the mechanism mode of karst collapse induced by it, using the examples of karst collapse events at Wanhao foundation pit and Diaoyutai foundation pit in Guigang City, Guangxi Zhuang Autonomous Region. The study utilized ground investigation, drilling, and groundwater/gas pressure monitoring. Findings of this study helped propose the prevention and control measures. The results indicate that the geological environment conditions in the research area are fragile and characterized with underground karst features, thin overburden, and abundant groundwater. The dynamic changes in the groundwater level within cones of depression caused by foundation pit drainage and rainfall recharge are identified as key factors contributing to geological disasters of karst collapse. The large-scale extraction of groundwater over a prolonged period is a significant human-induced factor contributing to karst collapse in the research area.