Collapse Mechanism of Shallow-Buried Karst Cave Under the Effect of Mining

Considering the surface collapse problem in shallow-buried karst mining area, the process and mechanism of karst cave and surface collapse were theoretically analyzed. The surface collapse process of shallow-buried karst was reconstructed through UDEC numerical simulation, and the causes for the development of open karst cave fissures were preliminarily discussed. Study results indicate that: the formation of open karst cave fissures is the prerequisite and basis for surface collapse, and whether the structure of the soil cave may remain stable is the key for whether the karst collapse will develop to surface. In response to this, in order to prevent surface collapse after the formation of open karst cave fissures, the overlying layer must be thicker than the sum of ultimate equilibrium height of the soil cave and the ultimate development depth of the earth fissures. Meanwhile, the formation of open karst cave fissures is mainly due to the reduction or unloading of horizontal pressure stress during the bending and subsidence process of the karst stratum. Based on the research achievements in this paper, cases of karst and surface collapse in the mining area were analyzed and discussed with Pinghu Mine as the engineering background, and the results indicate that the critical safety thickness of the overlying layer at No.1 and No.6 collapse sites in Pinghu Mining area should be at least 13.36 m. In this paper, from the point view of environmental protection, the development process and mechanism of shallow-buried karst collapse under the effect of mining were analyzed to provide directive significance for mining with coordination between environment and resources in karst areas.