Study On Reasonable Coal Pillar Size Of Gob-Side Entry In Thick Coal Seam Of No.1 Coal Mine

The reasonable size of coal pillar in thick coal seam section is one of the main factors affecting the safe and efficient production of underground coal mine in China.Aiming at the actual situation of thick coal seam mining in Pingshuo No.1 Coal Mine,this paper deeply studies the reasonable section coal pillar size under the influence of mining under the side.By means of field measurement,theoretical analysis,laboratory test and numerical simulation,the fracture characteristics of roof overburden rock,the evolution law and fracture characteristics of fracture field,the reasonable size of section coal pillar and the support of roadway surrounding rock are studied.The main research results of this paper are as follows :The physical and mechanical parameters of 4 # coal rock sample in Pingshuo No.1 Mine are obtained,which are class II stable surrounding rock.The maximum horizontal principal stress is10.98 MPa,and the direction is roughly N64.2 ° W direction.The structure of ’ low cantilever beam + high hinged rock beam ’ is formed above the goaf in the overlying strata of thick coal seam fully mechanized caving face in Pingshuo No.1 Mine,and the breaking position of the cantilever beam structure is 21.7 m from the coal wall of the goaf.The influence law of coal seam mining thickness on overburden fracture characteristics and the stress concentration degree of section coal pillar are obtained.The extension range of overburden fracture in lower coal seam mining is defined.The plastic bearing rate,vertical stress and roadway surface displacement of coal pillar under different coal seam thickness and different coal pillar width are analyzed respectively.Combined with the bearing characteristics of section coal pillar and on-site mining technical conditions,the size retention scheme of section coal pillar in 14118 working face is determined.Through the field industrial test,it can be seen that the stress of the surrounding rock of the roadway began to stabilize after 60 days of excavation,and the whole roadway was in a stable state.The bolt and anchor cable supported inside the roadway jointly carried the surrounding rock and ensured the stability of the surrounding rock of the roadway.The research results of this paper have important guiding significance for the retention of coal pillars in mine sections,and have certain guiding and reference significance for coal seam mining under similar conditions.