广州城乡建设场地岩溶地面稳定性评价

Stability Evaluation of Karst Areas in Urban and Rural Construction Sites

根据调查和勘察资料，分析了以广州市为例的隐伏型岩溶分布区的地质环境条件，岩溶塌陷特征和致塌因素。认为岩溶塌陷，是由于负地形开采石灰石矿坑和城市建设地下空间工程基坑排水，大幅降低地下水位过程所引发。文中应用多元逐步回归方法和专家经验公式，对广州岩溶发育区建设场地的稳定性进行评价，求得岩溶场地抽排水致塌时临界地下水位降深值。该临界值为9．25～12．5m，为一区间值。并认为当地下水位降深大于该临界值时，发生塌陷的概率较大，地下水位降深小于该临界值时，发生塌陷的概率相对较低。

According to geological prospecting and related survey data, the geological environment of karst areas in Guangzhou and features of karst collapse and factors that caused karst collapse are analyzed in this paper. It＇s found that karst collapse is mainly caused by significant reduction in groundwater levels due to negative terrain mining of limestone and underground space engineering in urban areas. Reduction in groundwater level leads to reduction of buoyancy and increase of body weight of cover soil. Such changes will result in soil deformation because of infiltration and subsequently ground subsidence. This paper analyzes the stability of construction sites in karst areas by applying multiple regression and empirical formulas created by other experts. The threshold of groundwater level descent is in a range of 9.25-12.5m. The probability of collapse would be much higher if the groundwater level drop is greater than the threshold, and that would be much lower if the drop is less than the critical range.