Analysis Of The Formation Mechanism Of Tanshan Coal Mine Goaf Landslide

Tanshan Town of Yuanzhou District is located in loess hilly landscape and rich inmineral resources. Therefore the underground mining in the region induced a large number ofmining moving landslides, in which Tanshan coal mining landslide is a typical one, seriouslyinfluencing the local economic construction and people’s lives and property. The analysis ofthe formation mechanism of Tanshan coal mine landslide not only is of great significance forthe prevention of geological hazards in Yuanzhou, but also provides a reference for the similarlandslides.Based on the data of the geological hazards detailed survey of Yuanzhou, the formationmechanism of Tanshan coal mine landslide was studied systematically via field investigation,laboratory test, theoretical analysis and numerical simulation. The main achievements are asfollows:1) The formation of Tanshan coal mine landslide was mainly controlled by physical andmechanical properties of rock and soil mass, goaf and precipitation and surface water. Jurassicmudstone made up the principle part of the landslide, which has the properties of highhydrophilicity, disintegration and expansion effect, providing the material basis for thelandslide; the goaf changed the stress field, which destroyed the rock mass and made it moveto the goaf. Then the tension crack appeared which made the seepage of precipitation moreeasily and in turn formed a weak belt between highly and intermediary weathered mudstone,and the landslide was finally formed.2) Numerical simulation showed that the landslide would not happen only affected bygoaf, which meant that precipitation and surface water was a non-ignorable factor. The resultcoincided with the actual situation when the weak belt had been set. The sliding process wasdivided into four stages: creep slip, distortion, strenuous movement and deposition.3) The finite element simulation of the slope before it slide showed that rock massmoved towards the goaf; in the back of the slope, the displacement of rock mass above theweak belt was significantly larger than the lower one, which meant that the landslide happened. The stress concentration mainly appeared above the goaf and around the weak belt.The maximum principle stress appeared in the edge of goaf where compressive happened andthe principle was negative which meant tensional failure happened.4) Limit equilibrium method and finite element method have both been taken to calculatethe stability coefficient. The result showed that the landslide was stable in natural state andbasically stable under rainfall condition due to the increase of the sliding mass and thedecrease of shear strength of the sliding zone. The finite element method accorded with theactual stress distribution better than the limit equilibrium method, so the calculation will bemore accurate using the finite element method.