Inversion Of Rock Mechanics Parameters And Study Of Surface Deformation Law In A Mining Area Of Shandong Province

Based on the research background of 4302 working face of a coal mine in Yuncheng County,Shandong Province,the surface deformation observation data of the working face are collated and analyzed by MSDFVS,the subsidence and horizontal movement curves of two observation lines are drawn,and the rock movement parameters such as inclination,curvature and angle of movement of the two observation lines are obtained.Based on the existing measured data and geological data,the numerical simulation model of 4302 working face is established by FLAC3D software.Combining the orthogonal test method with numerical simulation method,the mechanical parameters of the three main strata in the model are elastic modulus,Poisson’s ratio,cohesion and internal friction angle,taking A22 subsidence value,C9 horizontal displacement value and C line moving angle as test indexes.Inversion.After 27 groups of experiments,a group of parameters which are close to the measured data are obtained.In order to further determine the optimal parameters,the range of parameter selection is narrowed by four factors with greater significance,and the parameter level is redefined.A new orthogonal table is selected for the second orthogonal test,and a set of optimal rock mechanics parameters is determined.The numerical simulation results of these parameters are checked with the measured subsidence curve and horizontal movement curve,which proves the reliability of these parameters.Based on the rock mechanics parameters inverted by orthogonal test and numerical simulation analysis of 4302 working face,the rock displacement parameters such as maximum subsidence value and maximum horizontal displacement value are obtained,and the rock displacement parameter curves of strike and trend are drawn.Compared with the measured data,it is found that the rock displacement parameters obtained by numerical simulation are slightly larger than the measured data.The variation of the subsidence of strike and dip profile with the advancing of working face is analyzed,and the regularity of the subsidence of strike and dip is obtained.The variation of surface and overlying strata of 4302 working face and adjacent old goaf is analyzed.According to the results of numerical simulation,the subsidence range of village buildings above the working face under the influence of working face advance is analyzed,and the damage grade of village buildings is evaluated according to the horizontal deformation value of surface water.It is found that only a very small part of the village buildings are damaged grade Ⅱ,which is basically not affected by the mining of 4302 working face.Using FLAC3D software,under the condition of keeping the mining plan of 4302 working face unchanged,numerical simulation is carried out for the three factors of inclination length of old goaf,dip angle of coal seam and thickness of Quaternary system respectively.The influence of the change of each factor on surface deformation is analyzed,and the changes of surface rock movement parameters such as surface subsidence value,surface horizontal movement value and movement angle value under the influence of each factor are obtained.