Numerical study on seepage property of karst collapse columns under particle migration

摘要

Presently, there is an increasing number of water outburst accidents in China as mining activity continues to develop to deeper ground. In these accidents, water outburst caused by karst collapse columns often results in serious damage, involving both the loss of lives and significant economic loss. Therefore, it is of utmost importance to study the seepage property and water outburst mechanism of karst collapse columns. In this paper, based on the seepage theory and the groundwater dynamic theory of porous media, a fluid-solid coupling model for karst collapse columns was built and then imported into COMSOL Multiphysics to be solved, by considering the heterogeneity of rocks in karst collapse columns, and assuming that the porosity obey Weibull distribution, thus obtained the parameters, including porosity, seepage, particle concentration, water inflow evolution law. The research results indicate the following: (1) particles in karst collapse columns will be eroded and transported under the effect of fluid as the time, porosity, water inflow and particle migration velocity all increase rapidly, and eventually a main seepage channel will form; (2) the seepage capacity for karst collapse columns initially grows slowly, then water inflow increases gradually with the erosion and migration of the particles.