广西武宣土洞发育水动力条件评价

本文分析了武宣土洞发育的地质背景、水动力诱发土洞的过程，在理想条件下，建立了土体渗透破坏形成土洞的管道流机理模型，根据管道流理论，分析得出土洞发育水动力条件表达式。通过自行设计的管道流测试仪装置，进行管道流模拟试验，计算得出研究区土洞发育的临界切应力为21.20 Pa。运用电子扫描电镜技术，测试研究区孔隙等效直径为31.6 nm，计算得出研究区土洞发育的临界水流为0.530 cm/min。对比临界水流和现场监测的实际地下水流，评价土洞发育的可能性。结果表明，目前情况下，地下水流未达到临界值，不具备引起黏土流失形成土洞的水动力条件。

Assessment on the hydraulic condition of forming soil-caves collapse in Wuxuan,Guangxi, China

This paper analyzes the geological background and the process induced by the hydrodynamics of developing soil-caves in Wuxuan, a city in Guangxi Provence, china. Under ideal conditions, the mechanism model of the seepage failure of soil to forming soil-caves is the pipe flow. From the theory of the pipe flow, it establishes the expression of the hydrodynamics causing the soil-caves. Next, through the experiment designed to simulate the pipe flow, it obtains the critical shear stress 21.20 Pa to lead to soil-caves in the study area. The equivalent diameter of soil pores is 31.6 nm tested by the electron scanning microscopy. With the known parameters, it calculates the critical velocity of ground water 0.530 cm/min. Comparing the monitoring data of the ground water in the field with the critical hydraulic values, the study assesses the probability of the soil-caves collapse. The result shows that the current hydraulic condition doesn’t have enough the dynamic to form the soil-caves collapse in Wuxuan.