Study On Mechanism Of High Inclination Fault On Surface Deformation Of Goaf

At present,the mine environmental problems in our country are quite prominent,and the environmental problems faced by each mining area are different.The complex and changeable geological conditions of the mining area make its disaster-causing mechanism varied,Especially,the widely distributed faults not only increase the difficulty of coal mining,but also make the movement and deformation of overlying rock,soil and surface of goaf become complex and changeable,which greatly increases the difficulty of prevention and control of geological hazards in mining area.Based on this,this paper takes the two special surface deformation phenomena of Laohutai mining area in Fushun as the main research objects,which are the surface subsidence beyond the theoretical predicted value and the sudden change of the occurrence of the cracks in many linearly distributed houses.The influence of faults on the surface subsidence law of goaf is analyzed by means of field investigation,field test and numerical simulation.The main results of this paper are as follows:(1)Based on the analysis of the survey and design data of Laohutai mining area in the past,the number,distribution and occurrence of faults in the study area are counted and checked on the basis of sorting out the physical geography and geological survey of the study area.(2)Through data analysis and field investigation,this paper determines the specific location of theoretical prediction subsidence area and actual subsidence area,and finds the characteristics that the houses with abrupt fracture occurrence in the study area are distributed along faults.By using the methods of theoretical analysis,field test and quantitative calculation,the interference factors such as mine tremor,groundwater and repeated mining are eliminated.Combining with the results of field investigation,the main cause of surface special deformation in the study area is determined to be faults.(3)According to the relative position of faults and goaf,the relationship between faults and the influence line of strata movement angle and other factors,the influence of faults on the surface deformation range of goaf is introduced.At the same time,the concept of "dumping" is introduced according to the characteristics of fault distribution in Laohutai mining area.This paper holds that the main reason for the enlargement of the subsidence scope and the abrupt change of the occurrence of some house cracks in the study area is that under the influence of the goaf,the "flake granite body" formed by the cutting of several high dip faults on the north side of the F1 A fault in the subsidence area has undergone toppling deformation.(4)Two numerical simulation softwares,finite difference and discrete element,are used to simulate the movement and deformation of the overburden rock and soil in the goaf during the mining process.The failure and displacement characteristics of the rock and soil mass in the dumping area of the study area are analyzed through the distribution map of plastic zone,displacement nephogram and displacement trend map.The existence of the steep slope in the reverse direction is proved,and the mechanism of the dumping deformation is verified.(5)According to the characteristics of toppling deformation of rock and soil,the stability of the toppling area under the influence of faults is analyzed:(1)When there are several high dip faults on both sides of the influence line of strata movement angle in goaf,under the influence of the goaf,the area outside the influence line of strata movement angle may occur dumping deformation similar to that in the slope;(2)Under the influence of goaf,when the toppling deformation of rock and soil occurs,the fault only occurs local dislocation,but not overall activation;(3)When conventional goaf deformation occurs,a series of caving,bending,separation and subsidence occur in rock and soil body.However,when the toppling deformation occurs,the rock and soil mass moves as a whole,and it occurs quickly and lasts for a short time.Therefore,when the same scale of subsidence occurs,the overall stability of the toppling deformation block is better than that of the general subsidence area;(4)The differential settlement near the fault line belongs to sudden change,and the deformation is concentrated.The surface inclination value i is larger,and the damage to the house is more serious than the general situation;The subsidence of the interfault block is gradual,and the house deforms along with the overturned rock mass,which causes less damage to the house.The research of this paper can provide theoretical basis for the follow-up geological hazard control in Laohutai mining area and the future urban planning and construction of Fushun City,and also provide reference for the prevention and control of geological hazards in other mining areas with similar geological conditions.