| At present,my country’s large-scale state-owned mines "three-down" coal pressure exceeds 15 billion tons,and many eastern mines have coal pressure close to50% of the recoverable reserves.The situation faced by mining areas in Shandong Province is particularly severe.Zhaoguan Energy is located in Dezhou,Shandong.It has been mining for 11 years,with a cumulative recovery of 7.694 million tons.The current reserves that can be directly recovered are 56.329 million tons,of which only the amount of difficult-to-mine coal in the 111 and 211 mining areas exceeds 20 million tons,to realize the efficient exploitation of resources,has become a major engineering technical problem that Zhaoguan Energy needs to solve urgently.In order to study the evolution of cemented mining cracks and solve the problem of water inrush from the floor that may occur during the mining process,the thesis adopted laboratory tests,theoretical calculations,and numerical simulations,and achieved the following results:(1)The transportation and mechanical properties of the filling materials were tested,and the optimal ratio of the materials was obtained in the experiment.The ratios of the Yellow River silt and cement accounted for 85% and 15% of the dry material,respectively,which is the best,which satisfies the transportation and strength of the cemented filling material.(2)A set of experiments was designed to simulate the physical simulation of the first mining of the 11 th coal seam and then the 13 th coal seam,and the general law of crack evolution was obtained: when the 11 th coal was mined,the overlying rock on the roof changed little,and there were two downwardly developed cracks on the floor.3.5cm,the displacement of the overlying strata on the working face is small,only0.4m,and the roof of the working face is affected by the mining disturbance,and only the layered fissure zone and the curved subsidence zone appear,resulting in slight separation;in the 11 th coal mining When coal 13 is mined on the basis,the maximum height of cracks in the roof of coal 13 is 64 cm,which has penetrated 11 coals and developed upwards.A floor crack with a crack depth of 6cm appears,and the maximum displacement of the overburden is 1.81 cm.(3)Analyzed the mining geological conditions and hydrological characteristics of Zhaoguan Coal Mine.Based on the existing geological and numerical data,theoretical calculations were carried out on the cracks in the short-wall filling mining floor,and the failure depth of the mining face of the 11 coal mining face was 0.59 m.,13 coal filling mining face stope floor damage depth 1.79 m.(4)Combining the results obtained by FLAC3 D numerical simulation with physical simulation and theoretical calculation,the final results are obtained.After mining 11 coal,the maximum subsidence value of the overburden is about 0.4m,and the maximum depth of floor crack development is 3.5m;13 coal is mined After that,the maximum subsidence value of the overburden is about 1.81 m,and the maximum depth of the floor crack development is 6m.The experimental results show that it is feasible to mine 11 and 13 coal by short-wall cemented filling method,and it has no obvious impact on the surface buildings,and the possibility of water inrush from the floor is very low. |
