Physical Simulation Study On Genetic Mechanism Of Mining Landslide Under Rainfall Condition

Under the action of mining disturbance,the landslide caused by the deformation and damage of the overlying strata in the goaf is called the mining landslide.Since the reform and opening up,with the rapid development of China,energy demand has increased,all kinds of mining projects depth advance,and mining landslides are also increasingly frequent.In addition,recent years,heavy rainfall and other extreme weather increases,rainfall as an important factor in the landslide is also more prominent,caused many mining landslides under the rainfall condition.Seriously affected the safety and normal operation of mining area.Therefore,it is of important practical value and great social and economic significance to study the landslide induced by rainfall and mining.Based on these reasons,this paper take Madaling landslide in Qingshan mining area of Duyun City,Guizhou Province as an example.Based on the detailed field investigation,using physical simulation test method to simulate the deformation and failure process of the slope under the conditions of rainfall and mining,the whole process from deformation to instability was reproduced,and then study the Genetic Mechanism of mining landslide under rainfall condition.At the same time,provide some reference and theoretical support for the prevention and control of mining landslide.Mainly achieved the following research results:(1)The engineering geological conditions and the slope structure characteristics of the Madaling slope are identified.The stratigraphic in the study area is a gently counter-inclined layered structure,and the slope has the structural characteristics of upper-hard lower-soft,upper-steep lower-gentle and Soft and hard interbeds.The lower part of the slope developed 4 layers workable seam,and mining formed a large area of goaf.In the study area,Meidong slope developed five long cracks and the deformation of the slope is mainly controlled by the long cracks.(2)According to the results of field investigation,established the geological concept model and physical model of Madaling landslide.Based on the conceptual model,the conceptual model focuses on the soft and hard interbeds of the slopes,the structural planes and the generalization of coal seams.On the basis of the conceptual model,the motorized landslides are simplified and established the physical model with similar ratio of 1: 200.Orthogonal methods were used to perform similar material compounding tests,with similar material ratios for various lithologies.(3)The deformation and failure phenomena and the formation process of the sliding surface under the disturbance of the mining and the rainfall are simulated,and the whole process of the landslide from birth to development to the occurrence of the landslide is basically reproduced.Based on the comprehensive test results,the experimental process of rainfall stage is further divided into five stages: rainwater infiltration stage,rapid rise stage of water level,seepage output stage,instability stage and sliding stage.In addition,according to the test results,the rainfall threshold of Madaling landslide is about 230 mm.(4)Based on the field survey,physical simulation test and previous research results,the Genetic Mechanism of landslide under the condition of rainfall and mining disturbance is systematically analyzed.The Genetic Mechanism of this kind of landslide is summarized as follows: bending-tensile,plastic flow-tensile,creep-shear and landslide start.At the same time,it is found that the slip surface is basically formed along the vertical tensile fracture at the back of the slope,the goaf and the lower "ladder shaped" cracks,forming a complete sliding surface.(5)Based on the study of deformation and failure process and genetic mechanism of Madaling landslide,analysis and prediction the deformation and failure modes of Meidong slope and its process of deformation and failure,then provide some advice.The structure characteristics of Meidong slope is similar to Madaling slope and the deformation and failure Mechanism is similar too.It is possible to form a high-speed landslide with LF1 and LF2 cracks as the back wall and along the direction of 230 degrees.