Research On The Surface Deformation Caused By The Underground Mining Of The Bojianghaizi Coal Mine

In the process of coal mining,it will produce many problems about the mine geological environment. Among those problems, the deformation of the ground surface such as ground subsidence, subsidence and cracks has caused huge economic losses, which seriously restricts the sustainable development of mine economy and society. In order to reduce the losses caused by the surface deformation in mining process, the deformation mechanism and characteristics should be studied, and accurately predicting deformation is also important. Above these studies are the precondition to reduce and control the surface deformation, so to carry out the study on mechanism and prediction of surface deformation which is caused by underground mining has an important theoretical and practical significance. The work and conclusions of this paper are as follows:(1)This paper studied the Bojianghaizi coalmine’s surface deformation caused by underground mining, analysed the mechanism, influence factors, rules of its surface deformation. and pointed out the Bojianghaizi coalmine’s surface movement has the characteristics of hysteresis. This research showed that the buried depth of Bojianghaizi mine’ coal seam is very big, coal seam thickness is medium, overlying strata lithology is weak to semi hard. therefore, in the vertical profile,there are the three zone of the surface deformation. above all, in theory we can determine the study area’s ground deformation which is induced by underground mining will be relatively serious.(2) In this paper, probability integral method is used, and through the surface movement and deformation prediction system software, this paper predicted and calculated the surface subsidence value,mining field slope value, the movement and deformation value for nearly five years and more than five years in the study area. Prediction results were analyzed concretely, compared the deformation value of ground surface in the different period of time, made the land subsidence isoline map and horizontal deformation contour cloud map, analysed the deformation graph’s the characteristics. in the paper, the law of the earth’s surface deformation in the study area are summarized, I discovered that these two graph contour are closed oval, and the maximum dose is in the middle part, deformation value decreased gradually from inside to outside.it shows that the sinking value above the center of the goaf area is the largest, but the horizontal deformation value is the smallest. The effect of the different working face’s mining on the overburden is mutual. The value of the ground surface deformation of the same area is several working face’s mining interaction results’ superposition.(3)Combined with deformation forecast results of the study area, the study made a mark on some area where may produce cracks in the surface horizontal deformation isoline chart and the land subsidence isoline map. Aiming at collapse, cracks and other geological disasters which are caused by underground mining in the study area, focus on disaster prone areas, corresponding measures of prevention and control engineering are proposed, so that, an effective basis was provided for controlling the ground subsidence and ground fissures disaster, which may appear in the mining process of the Bojianghaizi coalmine in the future.