Study And Application Of Surrounding Rock Control Technology For Gob-side Entry Retaining In 3405 Working Face Of Xinyuan Coal Mine

With the progress of the construction of resource-saving society in China,the recovery rate of coal resources has become a key focus of coal mine enterprises.Gob-side entry retaining,as one of the ways of roadway protection without coal pillar,can not only greatly reduce the loss of coal pillar left in goaf,for high-gas mines,it can also change the air flow of the working face,thereby solving major safety issues such as gas accumulation at the corners of the working face and the roadway,and gas overrun in the goaf.Because the influence time of two times mining on roadway is so long,surrounding rock stability control of gob-side entry retaining has always been the focus of attention of coal enterprises,experts and scholars.In this paper,the methods of field drilling peep,physical and mechanical testing,mechanical model analysis,numerical simulation inversion and field industrial test are used to systematically analyze the structural characteristics and fracture development law of roof surrounding rock,measures the physical and mechanical parameters of coal and rock mass,analyzes the periodic activity law of basic roof of gob-side entry retaining,the possible location of basic roof fracture line,determines the parameters of roadside filling body,roadside filling body reinforcement technology,and analyzes the temporal and spatial evolution law of surrounding rock deformation of gob-side entry retaining by numerical simulation.The main conclusions are as follows:(1)Through the construction of peep holes on the roof of the roadway,the peep instrument was used to analyze the structural characteristics of the surrounding rock of the roof rock and the development of cracks;the physical and mechanical properties and parameters of coal and rock mass were tested in the laboratory.(2)Based on the basic roof fracture model,the possible location of the basic roof fracture line is analyzed,and the engineering geological condition parameters of 3405working face are brought into the relevant formula calculation.The theoretical results show that the basic roof fracture of gob side entry retaining occurs above the coal body.(3)The numerical calculation model of filling body is established by UDEC software,and the distribution of plastic zone,fracture propagation characteristics,stress evolution and deformation law of filling body under different supporting schemes are analyzed.The parameters of filling body of high-water material are determined as follows:width 2.0 m,water cement ratio 1.5:1,placed in goaf side 1.6m.Based on the reinforcement mechanism and numerical calculation model,the reinforcement technical scheme is determined:the diameter of split bolt is 22 mm,and the spacing between rows is 800×800 mm.(4)By using FLAC^3Dnumerical simulation software,the space-time evolution law and deformation characteristics of 3405 auxiliary air intake chute gob-side entry retaining roadway under the determined roadside support and reinforcement scheme are inversed,and the control effect of the scheme on surrounding rock of gob-side entry retaining roadway is verified.(5)This scheme is applied to the engineering practice of auxiliary air intake along the channel at 3405 working face of Xinyuan Coal Mine.The field observation results show that the deformation of gob-side entry retaining is small,in the range of80 m behind the working face,the roof subsidence of gob-side entry retaining remains relatively stable,the engineering application effect is generally good,and the later use of the tunnel meets the requirements.There are 50 pictures,12 tables and 134 references.