Study On Flexible Anchor Support Technology With High Prestress

The control of surrounding rock stability of complex and difficult roadways(especially loose surrounding rock,local voids,tectonic stress and so on)is a major problem that restricts the current deep coal mining.Such roadways often show problems such as large deformation of surrounding rocks,easy failure of roadway support components,high repairing frequency and easy floor heave.Therefore,it is urgent to seek new breakthroughs in new support technology and new support methods in order to effectively control harmful deformation of complex and difficult roadways,ensure the normal use of roadways,and reduce roadway support costs.Therefore,with the help of numerical simulation software FLAC3 D,this paper comprehensively studies the flexible anchorage support technology based on high prestressing force for 2603 transport roadway under complex and difficult conditions by using the methods of theoretical analysis and field measurement,and achieves the following main results:(1)The structure of roadway roof surrounding rock is peeped by using mine electronic borehole peeper: the structure of roadway roof surrounding rock is poor,cracks are obviously developed,and a small number of holes exist in the local old roof;the deformation and failure characteristics of roadway surrounding rock are summarized and the problems existing in this kind of complex and difficult roadway support are analyzed.(2)Based on the analysis of geological conditions of 2603 transport roadway in 480 mining area of Zhangcun Coal Mine in Luan mining area and the investigation of support of deep high stress coal roadway under similar conditions in other mines,the concept and support theory of flexible anchorage support based on high prestressing force are put forward.The principle and support method of flexible anchorage support based on high prestressing force are systematically analyzed,and the principle of flexible anchorage support based on high prestressing force is determined.The key technology of flexible anchorage support based on high prestressing force is given.(3)With the help of numerical simulation software FLAC3 D,the key parameters and pressure relief parameters of flexible anchorage support based on high prestressing force are simulated and analyzed,and the reasonable support parameters(mainly the pre-tightening force value of anchor bolt and cable,the selection of anchor cable specifications,etc.)and pressure relief parameters(the layout of pressure relief boreholes in roadway floor,borehole diameter,length,row spacing,etc.)are finally determined.(4)Based on the high prestressing flexible anchor support technology,the industrial test was successfully carried out in 2603 transport roadway of 480 mining area of Zhangcun Coal Mine.Through feedback of field measured data,it was concluded that:(1)the displacement of roof and floor of 2603 transport roadway and the displacement of both sides increased first and then remained unchanged with the increase of time,that is,the deformation of roadway was large at the initial stage of excavation,and the roadway was about 40 days later.In addition,the roadway surface displacement is within the allowable deformation range,which further illustrates the rationality of the optimization scheme of flexible anchorage support technology based on high pre-stress.(2)The monitoring results of bolt and cable in 2603 transport roadway by non-destructive testing technology show that the quality of bolt and cable is excellent,and the supporting condition of the whole supporting system is good.