Risk analysis of a closed limestone mine geological environment in Fengshan county, Southwest China

摘要

There are many closed limestone mines in Fengshan county, Guangxi autonomous region, Southwest China. The geologic environment in the mining area had been destroyed during the mining period without carrying efficient environment governance and land restoration. In order to mitigate the potential geological hazard risk induced by the closed mines, one representative closed mine is chosen to carry out the research of risk analysis. In the paper, firstly, the mine is divided into different zones according to rock mass structure, and geological environmental problems have been analyzed in each zone. Secondly, the failure mode and risk level are analyzed and determined by comprehensive methods of stereographic projection, rigid limit equilibrium method and numerical simulation (by using FLAC3D and ROCKFALL software). Lastly, risk assessments for the closed mine geological environment are proposed. The analysis shows that the mining face can be divided into eight zones(number from I to VⅢ), which are mainly composed of intact rock, blocky rock, thick platy rock, karstified rock and rock block accumulation body. The major risk in the area comes from rock collapses and rock falls on the mining face. Most of rock collapse will occur in the zone I and E. Rock fall will occur in the zone I to zone VI. The highest risk will occur in the zone I, E and Ⅷ.