炭质灰岩地区抽水致塌控制因素和影响因素--以广西兴安县为例

Controlling and influencing factors of the karst collapse caused by withdrawing of groundwater in carbonaceous limestone area:A case study of Xing'an County,Guangxi Province

为研究炭质灰岩地区抽水致塌控制因素和影响因素,通过电法物探、地质钻探及抽水致塌试验相结合的综合手段,对兴安县石炭系下统岩关组(C1y)炭质灰岩地区的岩溶塌陷进行关联分析,建立降深水位与时间、恢复水位与时间的关系对比曲线。研究结果表明:在炭质灰岩地区进行抽水活动时,其主要补给源为小溶洞内储存水,运输通道为岩溶裂隙;该炭质灰岩地区岩溶裂隙具有不规则性,因此,在同类地层中测得的渗透系数k及影响半径R有较大差异;研究区域内抽水致塌的位置受地质构造的影响较为明显;钻井人为抽水致塌受多种因素共同作用影响,而地下水位升降为主要影响因素。

For the study of the model of pumping collapse in carbonaceous limestone area,through the combination of electrical geophysical prospecting,geological drilling and pumping collapse test,this paper conducted the correlation analysis of karst collapse in carbonaceous limestone area of Lower Carboniferous Yanguan formation(C1y)in Xing’an County,and established the correlation curves between drawdown water level and time and recovery water level and time.The results denotes that:The main supply source is water stored in small karst caves and the transfer passage are cave and karst fissures when pumping in calcareous limestone area.The karst fissures in the calcareous limestone area are irregular,so the permeability coefficient and influence radius measured in similar strata are quite different.The location of collapse caused by pumping in the study area is obviously affected by geological structure.When pumping produces excessive drawdown,the karst collapse often occurs at the fracture zone of aquifer.The collapse caused by man-made pumping is affected by many factors,and the rise and fall ofgroundwater level is the main factor.