抽水引起岩溶区路基塌陷的机理分析及其控制

土洞的形成与扩展是产生覆盖型岩溶地面塌陷的前提,为了研究人工抽水引起的岩溶区路基塌陷的机理,用解析法分析了土洞扩展的条件,提出了剥落力的概念,认为土洞的向上扩展是剥落力大于土体抗拉强度的结果。剥落力σb是时间和空间的函数,土洞周边不同的点,受抽水引起的剥落力是不同的。土洞一旦开始向外围扩展,由于剥落力越来越大,所以土洞呈现发展趋势。当抽水使地下水位下降时,剥落力σb增大。因此,岩溶区抽水时必须控制水位降深、流量,从而最大限度地避免路基土洞和岩溶塌陷的产生。

A Study on Mechanism of Karst Collapse of Subgrade Induced by Pumping and It's Control

The forming and expanding of a soil cavity are the base of the overburden karst collapse.For the purpose of the study of mechanism of karst collapse induced by pumping,the conditions of soil cavity expanding are analyzed by analytical method,and the concept of spalling force is put forward.The spalling force is the function of the time and space,the spalling forces caused by pumping water are different at different point around the soil cavity.When the soil cavity propagated outwards,the soil cavity become a accelerating development trend because of the increasing spalling forces.When pumping water makes the underground water drop,the spalling force increases.Therefore,the factors of pumping such as depression depth of water level and flow volume must be controlled in karstic area,so that the forming of soil cavity and the karst collapse of subgrade can be avoided.