| In recent years,with the advance of ecological civilization construction,geological environment and ecological restoration in mining subsidence areas have gradually become the focus of social attention.Beiminghe iron mine,located in wuan city,hebei province,is mined by sublevel caving method.With the development of underground mining,surface subsidence also occurs,and the mining subsidence area becomes larger and larger.Since the collapse pits began to appear near the measure well in 2003,the extent of surface dislocation has increased with the expansion of the mining area,and the central area has been slowly sinking.In order to effectively repair the geological environment of the surface subsidence area,and reasonably formulate the control measures,the stability of the mining subsidence area is analyzed by field investigation and numerical simulation.Field investigation showed that the southern edge of the final dislocation range of the subsidence area was 60 m away from the north bank of beiming river.The final dislocation area is 1250 m from east to west and 850 m from north to south,with a total area of about 1.24km2.The subsidence area is estimated to have a volume of 2.76 million m~3.The terrain of the area west of line 11 in the subsidence area presents an overall subsidence basin and the subsidence is basically stable.The ore body in the area east of line 11 to line 8 is the thickest and the main collapse area.The sublevel caving mining method without pillar is adopted for mining and the upper part of each sublevel is in good natural caving condition.The collapse of the upper overburden strata was divided into two phases.The first phase was the stop-go collapse during underground mining,which was caused by underground mining.The collapse of the second stage is caused by the collapse of the first stage,which causes the overburden of the ore body to form a huge fault surface in the vertical direction due to its own weight,resulting in the overall subsidence of the overburden of the ore body.The sublevel caving method without pillar is adopted for mining and the upper part of each sublevel is in good natural caving condition.The collapse of the upper overburden strata was divided into two phases.The first phase was the stop-go collapse during underground mining,which was caused by underground mining.The second phase is the collapse of the first phase,which causes the overburden of the orebody to form a huge fault surface in the vertical direction due to its dead weight,resulting in the overall subsidence of the overburden of the orebody.A three-dimensional geophysical and surface subsidence model is constructed.Four kinds of cases are analyzed when the subsidence acceleration of the void area increases suddenly.Numerical simulation method was used to analyze the stability of subsidence area,and the results showed that the stress and strain of underground surrounding rock far exceeded the allowable stress and strain of surrounding rock in the east direction of the middle part of subsidence area(no.11 exploration line),and the surrounding rock was in collapse state.The underground mining area under the subsidence area between No.9 ～No.13 exploration line has collapsed to the surface,and the subsidence area tends to be stable.Gradually fill the subsidence area,the upper pressure of the collapsed goaf will gradually increase,and the total pressure will increase by 1.62%.After filling materials in the subsidence area,it will play a compaction role on the collapsed goaf and will not cause a large area collapse.Figure 49;Table 11;Reference 57... |
