ISSN 1003-8035 CN 11-2852/P

    广东佛山市高明区李家村岩溶塌陷群成因机理分析

    Analysis on the formation mechanism and development process of karst collapses in Lijia Village, Gaoming District of Foshan City

    • 摘要: 以自然诱发的李家村岩溶塌陷群为研究对象,在系统收集区域地质、构造、工程、水文、环境、气象、历史灾害等资料的基础上,结合钻探揭露结果,查明了李家村岩溶塌陷群所在区域地质环境条件和岩溶发育特征,分析了形成过程,并探讨了成因机理。结果表明:(1)李家村岩溶塌陷群所在区域覆盖层为带“天窗”的“隔−透”交替型地质结构、基岩可溶岩砾状灰岩中方解石含量高易溶蚀,为土洞和溶洞形成和发展起到决定性作用;北东向和北西向断裂交叉叠加作用、紧靠西江和存在古河道,为地下水潜蚀强径流和频繁交换提供通道,对岩溶发育起到主导作用;地表水和地下水连通性好有助于降雨诱发岩溶塌陷;(2)李家村岩溶塌陷群的发生过程经过三个阶段:前期水渗气压阶段→中期软化塌陷阶段→后期振动群塌阶段,致塌模式属渗压−重力−软化型。(3)李家村岩溶塌陷群是在特殊的“岩−土−水−气”组合地质环境条件下,由强降雨作用诱发并导致土洞垮塌而引起一连串自然塌陷所形成的。

       

      Abstract: Taking natural-induced Lijia Village karst collapses as the research object, on the basis of systematically collecting the data of regional geology, tectonic geology, engineering geology, hydrogeology, environment, meteorology, historical disasters, combined with the drilling data, the geological environment conditions and karst development characteristics of Lijia Village karst collapses come to a conclusion, and its formation process is analyzed. Finally, the genetic mechanism is discussed. The results indicate that: (1) The overburden in the area where the Lijia Village karst collapses located is an alternate geological structure with “Skylight” and “Separation”, and the content of calcite in rudstone is high and easy to dissolve, which plays a decisive role in the formation and development of soil caves and karst caves. The intersection and superposition of the NE fault and NW fault, closing to Xijiang River and the existence of ancient river channels, provide a channel for groundwater erosion and strong runoff and frequent exchange, and play a leading role in karst development. Good connectivity between surface water and groundwater directly leads to rain-induced karst collapse. (2) The process of karst collapses in Lijia Village is divided into three stages: water pressure stage in the early stage, softening collapse in the middle stage and vibration group collapse in the later stage. The collapse model is Osmotic Pressure-Gravity-Softening. (3) The karst collapses in Lijia Village is formed by a series of natural collapses induced by heavy rainfall under the special geological environment of “rock soil water gas” combination.

       

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