Analysis And Prevention Of The Formation Mechanism Of A Ground Collapse Induced By Mining In Maanshan City

Ground collapse is a kind of geological disaster,which endangers national economic construction and people's life safety.The causes are diverse.The karst development and the mining collapse are mostly.This paper is based on a geological disaster of ground subsidence in Maanshan,and analyzes the regional geological conditions.,geophysical exploration,static penetration,engineering geology,ground subsidence observation and groundwater level observation,etc.,systematically analyze the formation causes of the ground collapse,and initially establish a quantitative analysis of the collapse mechanics model,and propose prevention measures:1.Through transient electromagnetic sounding(TEM),natural electric field method,IP sounding,high-density electrical method and cross-hole resistivity CT imaging,the thickness and geological structure of the cover layer and its vicinity are preliminarily identified.The lithology of the strata changes;through the drilling project,the underlying bedrock strata of the Quaternary in the subsidence area are mastered as volcanic clastic rocks,ie tuff,with no ore body distribution,and the ground collapse caused by karst development and mine callus is ruled out.The possibility of destruction;2.Through the drilling,static exploration and comprehensive geological survey work,the lithologic lithofacies variation characteristics and geotechnical geological properties of the bedrock and overburden in the exploration area were ascertained.The rock and soil in the area is divided into loose rock group(NT)dominated by cohesive soil,rock group(Hs)dominated by tuffaceous clastic rocks,fine clastic rock composed mainly of siltstone and mudstone.Group(Sf)and neutral rock group(Qd)dominated by diorite;3.Through the construction of borehole water level observation data,it was found that the dewatering and drainage funnels in a nearby stope produced significant differences in the water levels of different aquifers in each aquifer in the zone,combined with the original long hole drilled beside the collapse zone.Pore structure and water level observation and analysis to determine the cause of ground collapse damage in this area.That is,the head pressure of the upper aquifer and the lower layer of gravel confined aquifer changes,resulting in changes in the stress field,causing changes in the permeability of the rock and soil.The changes in hydrostatic pressure and hydrodynamic pressure generated by groundwater seepage directly change the stress state of the rock and soil.The shear deformation and displacement of the rock and soil are realized,the sludge is transformed into rheology,and the sand is infiltrated and deformed.The change of groundwater dynamic field is caused by the drainage of the surrounding mines,and the passage of the formation of the seepage deformation and rheology is mainly caused by the through action of the long view hole;4.In the high-risk area of the ground collapsed in the area,72,713 m2,and comprehensive measures for “avoiding relocation,drilling and plugging,land reclamation,control construction and ground deformation monitoring” were proposed.