The Law Of Overlying Rock Strata Movementand Surface Deformation Under Repeated Mining At Buertai Coal Mine

With the development of coal enterprises in our country,the mining depth is increasing year by year,repeated mining problems also became more and more serious.To study the surface movement and deformation law and failure characteristics under the condition of repeated mining.Combined with the corresponding simulation software to discuss the damage characteristics of overlying strata by the corresponding simulation software to discuss the damage characteristics of overlying strata,this paper take Buertai Colliery as an example,which is located in Shendong mining district operated by Shen Hua coal group.The main content is as follows:(1)By establishing of corresponding surface movement and deformation observation based on 42105 repeated mining panel in Buertai mine,the surface subsidence were measured.According to the date of observation,the corresponding movement and deformation curve was draw,and the law of surface movement and deformation in the process of repeated mining were analyzed.We confirm the angle dimension parameters of ground movement by adopting the special points and probability integral.The results show that the surface subsidence scope is biger,horizontal displacement coefficient is larger,the time of ground movement and deformation is shorter under this geological condition.(2)Comparing with the theoretical calculation and simulation results,the “two zone” height was determined.The result show that the height of transmission fissure zone after mining coal seam 2-2 is 39~44.6m;The transmission fissure zone height is 60~66m,while the height of transmission fissure zone after repeated mining is 49~70m.(3)The ground movement and deformation under the conditions of repeated mining was studied at Buertai Colliery by using FLAC3d(Fast Lagrangian Analysis of Continua).When the lower 4-2 coal seam was mined,the original stable points in the ground again start to sink,subsidence is relatively more intense,subsidence coefficient increases,the old gob activate,and mining influence scope further increases and the activation coefficient.After the surface movement deformation became stability,the maximum subsidence value of different strata along with the change of buried depth is not uniform,but presenting a nonlinear curve,the change of the maximum subsidence value by fast slow down along with the increase of buried depth and the rock maximum subsidence value increase quickly with the increase of buried depth when buried depth exceeds a certain value.The study has great guiding significance on mining safety,predicting and controlling the ground surface movement in the similar geological conditions.