Yunnan The Lancang Old Factory Lead-zinc Roadway Stability Analysis

Laochang lead-zinc mine is an important smelting base of lead-zinc and silver habitat in Yunnan Province. It's a major source of economic development and financial income in lancing lahu minority—a unique Lahu Nationality town in Lancang, in China. Meanwhile, it's the largest scale existing lead-zinc ore in south-west of Yunnan. With the development of the mining to the deep, the roadways distort strongly, puking and side wall collapse are serious. The main roadway of mining and transportation passed through a part of the adjacent rock. The rock was soft and fragment, and expansion when it was exposed to water, extremely easy to weathering and collapse. It leads to the roadway transportation be unable to carry on normally. The issue of the roadway stability has become one of the important problems of constraining mine production and mine safety. Therefore, the thesis is carried on.Based on the previous studies, the paper researched the roadway wall rock in Laochang mine. The wall rock's engineering geological condition, hydrogeological condition and deformation characteristics were deeply and carefully researched by field geological survey and laboratory analysis, which got the fundamental factors of influencing the stability of roadway. Combined with the practice, classification standard of engineering rock, standardize the classification of water conservancy and hydropower, and RMR classification were applied to qualitative and semi-quantitative appraise the roadway wall rock. The roadway wall rock were classified into IV and V in Laochang mine. The stability of the wall rocks were analyzed and evaluated. Generally, the rock of type IV belongs to hard and medium hard rock, which doesn't require support. The rock of type V belongs to soft rock, which is expansion when exposed to water, easy to weathering, behaves instability and need support. At the same time, according to the physical mechanics experiment for rocks of different quality, physical mechanics parameters was obtained. FLAC model was applied for excavating tunnel in order to carry on numerical simulation. Redistribution characters of wall rock's stress and the tendency of deformation were simulated after excavating the tunnel. The numerical simulation results show that the concentration sites of wall rock stress of roadway was in the both sides of base angle and the local range of 1-2m away from the direction of the roof-to-floor. Wall rock of deformation was andesite-tuff; deformation of the region was mainly in roof-to-floor and both sides and the center of the roof and floor; the instability factors of roadway were rock nature, water, geological structure, geostress etc. Generally speaking, qualitative analyses dovetail closely with the results of numerical simulation, which have some guiding significance theoretically for supporting the roadway and controlling the distortion.