Study On The Rock Movement Characteristics And Surface Deformation Law Of An Iron Mine Underground Mining

Roof damage and surface subsidence caused by underground mining has always been one of the problem.There are many metal mines at home and abroad underground mining caused roof instability?surface subsidence and so on,so it is very necessary to study this aspect of mine.Study and grasp the influence of underground mining activity on rock strata?the Laws of the Earth's surface,it has certain guiding significance for mine work.In this paper,the actual underground mining of sublevel caving without sill pillar in an iron mine is taken as the engineering background.Through the use SURPAC?FLAC^3D of the numerical model and numerical simulation.The deformation law of roof strata and surface in different mining depth is analyzed.And the use of roof caving?surrounding rock stress?displacement and a variety of monitoring methods for monitoring the stability of roof surrounding rock and surface.The main contents and conclusions of this paper are as follows:?1?Through collection of mine data and rock mechanics test,etc.Preparing physical and mechanical parameters of ore and rock for follow-up study?2?Through the theory of mining subsidence and underground mining,the basic laws of strata movement and surface deformation caused by underground mining are analyzed based on the actual mining background.The main movement form of roof strata in this iron mine is caving,variation of surface movement and buried depth of orebody?void size?mining depth and other factors.With the help of the fall model,further analysis shows that the caving belongs to the"flow around"model.The critical span of roof rock collapse in Goaf is about 140m,the change curve of roof strata thickness with mining depth is H=0.467L+5.21.Using key blocks and the AKABIRA projection theory,the characteristic parameters of key blocks are calculated,The possibility of rock mass sliding is obtained.?3?Through the use SURPAC of building orebody and surface model,FLAC³DD numerical simulation of roof and surface stress at different mining depth and before and after filling?change in displacement.It can be seen from the simulation results that the mining depth is directly proportional to the size of goaf,the influence degree of roof strata and surface is also proportional to it,the upper panel is affected more obviously than the lower panel after mining;After filling the existing empty space,the stress and displacement are controlled to a certain extent;After full stoping of ore body,surface subsidence displacement is the main phenomenon.?4?Through the combination of various monitoring means on site,Monitoring roof falling data?stress and displacement data of surrounding rock.According to the results of roof caving and on-line monitoring,the main caving area is located in 1-string?4-string?0-string,the range of variation is 0.02m-0.37m;The change of stress and displacement is mainly in the region of4-string?0-string?6-string,the range of variation is 0.1MPa-1MPa?0.2mm-13mm;the results are in good agreement with those of numerical simulation.?5?Through the result of surface monitoring indicate:The amount of GPS subsidence monitored by elevation is within 11mm,the general result of displacement variation at surface monitoring points is within 10mm;Control surface monitoring point over eastern airspace X and Y of the directional displacement variation is averaged at 5.5mm and 3.6mm,there is no abnormal deformation of the whole surface.