| According to the gob side entry retaining project in Gaohe mine,remnant analyzed and summarized the control experience of surrounding rock of gob side entry retaining obtained from the field investigation,grasped the law of the change of the bolt force through the non-destructive testing analysis of the bolt force.and put forward the "asymmetric support" optimization scheme.The parameters of the numerical model are verified by the measured data,the support parameters are optimized,the optimization scheme is determined and the field industrial test is carried out successfully.The main conclusions are as follows:(1)According to the field investigation and analysis,due to the high support strength of the roadway,the surrounding rock deformation of the roadway is often more serious during the period of retaining the roadway along the goaf and the influence of the secondary mining,and the deformation of the roadway is not obvious during the mining of the working face;in experience,the surrounding rock control difficulty of the gob retaining roadway in the working faces of w1309 and w1310 is lower than that in the working faces of w1319 and e1303,which is conducive to the optimization of bolt support parameters and is appropriate In order to reduce the cost of gob side entry,it is necessary to consider the change of surrounding rock conditions and optimize the parameters on the basis of full test and evaluation.(2)In this paper,the mechanism of nondestructive testing of bolt stress is analyzed theoretically,and the vibration parameters of bolt are calibrated through laboratory tests.The nondestructive testing of bolt stress is carried out during the mining period of the air intake roadway and the gob side retaining roadway of w1309 working face respectively.It is found that during the mining period,due to the good coal integrity and small deformation of w1309 working face,the average value and fluctuation value of bolt stress are not large,and the bolt stress is small The force did not increase sharply with the advance of the working face;after entering the gob side retaining roadway,the stress of the coal side bolt will increase significantly,and the stress of the opposite tension bolt in the filling body beside the soft mold concrete roadway will not increase significantly,which has not played the expected role in the tension bolt.At the same time,it also shows that in the control of the surrounding rock of the gob side entry,the deformation of the coal wall needsto be paid more attention to,and there is a waste of support under the current support strength.(3)This paper puts forward the optimization method of bolt support parameters in gob side entry based on bolt stress nondestructive testing,that is,"original scheme nondestructive testing and analysis optimization scheme and numerical calculation application feedback",and puts forward two optimization schemes of bolt support parameters.(4)The FLAC3 D numerical model is established,and the numerical simulation parameters are verified by the actual measurement data of surrounding rock deformation and bolt stress during the mining and gob side entry retaining of w1309 working face,which is used to optimize the bolt support parameters of w1310 working face.From the numerical simulation results,the two optimization schemes can effectively control the deformation of the surrounding rock,and the second scheme has more technical and economic advantages.(5)Through the analysis of the observation results of roadway surface deformation and bolt stress test data,the optimization scheme can give full play to the role of bolt support structure,reduce the cost of roadway support on the basis of controlling the deformation of gob side entry,and has a strong promotion significance in similar conditions.This paper contains 55 pictures,16 charts and 103 references. |
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