Research On Stability Mechanism And Control Technology Of Small Coal Pillars In Yang Chang Wan Coal Mine Ining Engineering

As the depth of coal mining increases,intensification of ground pressure,leaving large coal pillars to protect the prepared roadway,which not only causes a lot of waste of coal resources,but also triggers a series of power disasters,and studies the mining of small coal pillars along the gob-side entry Technology has a very realistic and necessary significance for the safe and efficient mining of deep mines.The paper uses field measurement,physical similar material simulation experiment,numerical calculation analysis,theoretical analysis and other methods to systematically study the stability mechanism and control technology of small coal pillars along the goaf.The main results are as follows:(1)According to the characteristics of “large and small structure” of surrounding rock in the roadway along the goaf,the mechanical model of the triangular block structure along the goaf is established,and the fracture location,strike length,lateral fracture length,etc of the curved trian gular the main parameters.The five fault structures of the overlying strata in the roadway along the goaf and the deformation and failure characteristics of the surrounding rock of the small coal pillar roadway along the goaf are determined.It reveals the instability of the top and bottom plates along the empty roadway,the instability of small coal pillars,and the instability mechanism of the semi-arched small structure of the hinged rock.(2)According to the numerical simulation results,the pressure step of the working face,the evolution process of the roof structure of the stope and the mining pressure characteristics of the working face are determined.Combined with the internal and external stress field theory of the surrounding rock support pressure distribution,the internal and external stress field division of the lateral support pressure of the coal roadway along the empty roadway iscarried out.According to theoretical calculation and on-site monitoring,the "internal stress field" of the working face support pressure is 9.5~11m.A small coal pillar retaining technology for excavation within the internal stress field is proposed.The width of the coal pillar along the empty roadway is designed to be 6m.The side of the coal pillar of the roadway is completely within the internal stress field.The solid coal side is at the edge of the internal stress field,and the trapezoidal section is adopted along the empty roadway.(3)Through the numerical simulation method,the influence of working surface engineering disturbance on the stability of small coal pillars and roadway surrounding rock is studied,and the stress and deformation characteristics of the surrounding roadway during excavation and mining are analyzed.It is found that the overall stability of the roadway is better during the roadway along the gob.The anchor cable and anchor can meet the requirements of the force.The roadway is in the low horizontal stress zone.The maximum subsidence of the roof is 11.4cm,and the displacement of the small coal pillar is 7.5cm.The solid coal is displaced by 6.8cm and the bottom drum is 4.5cm.The vertical stress of the two sets is greater than the vertical stress of the top and bottom plates.It is found that during the recovery of 130205 working face,the front coal wall 0~4m is the plastic zone and the low stress zone,4~10m is the plastic zone and the high stress zone,10~14m is the stress score zone,and 14~50m is the stress high value zone.In the slow-down zone,the depth of the coal wall is 0~1.5m,which is the tensile and shear plastic zone,which is prone to coal wall slabs.(4)According to the numerical simulation results,the 130205 working face is divided into five areas,namely the first potential danger zone,the second potential danger zone,the third potential danger zone,the fourth potential danger zone and the common zone.In the potentially dangerous area,potential danger zone and other areas,three coal pillar reinforcement and reinforcement schemes are designed to determine the support parameters of each reinforcement and reinforcement support scheme.After the implementation,on-site monitoring showed that the expected results were achieved and the normal operation of the mining work was guaranteed.The research results of this paper ensure the continuous mining of the mine,and have achieved satisfactory technical and economic effects.It also provides certain reference value for the design,reinforcement support and surrounding rock control of the roadway under similar conditions.