Research On The Determination And Control Technology Of Narrow Coal Pillars In Gob-side Driving In Limin Coal Mine

The reasonable setting of coal pillar size of gob-side roadway in fully mechanized mining face is not only related to the safety of mining face and the stability of roadway,but also one of the main problems of safe and efficient mining at present.When designing the width of coal pillar,the high stress environment and waste of resources caused by the large width of coal pillar and the serious production accidents caused by the instability of surrounding rock of roadway due to the narrow width of coal pillar should be fully considered.In view of the above problems,this paper makes a systematic study on the reasonable design of coal pillar width and roadway support parameters of fully mechanized working face in Limin coal mine,aiming at the condition of coal pillar setting in gob-side roadway of fully mechanized working face.By means of laboratory test,theoretical analysis,regression analysis,numerical calculation and industrial test,the physical and mechanical parameters of coal rock samples in limin Coal mine 1030901 working face are obtained.The structural characteristics and migration rule of surrounding rock in gob-side excavation of fully mechanized mining face are analyzed,and the mechanical structure model of arc-shaped triangular key blocks is established.The relative space position of roadway along goaf is about 12.3m.Starting from two dimensions of macro and essence,six regression analysis factors affecting the width of coal pillar in roadway protection are summarized.The correlation degree and mathematical correlation between regression factors and coal pillar width are studied by Matlab software,and a regression prediction model is established to preliminarily determine the size range of coal pillar in roadway protection.On this basis,8 different calculation schemes of narrow coal pillars were designed in combination with numerical simulation.The stress field and surrounding rock displacement distribution of gob-side roadway were analyzed,and the reasonable coal pillar width of gob-side roadway was comprehensively determined as 5m.Aiming at the large deformation problem of shallow surrounding rock of roadway and surrounding rock of pillar wall after excavation,the asymmetric bolt-net-cable combined support scheme is proposed.According to the field industrial test,the monitoring data of the roadway surface movement and the force of anchor bolt(cable)are analyzed.The deformation of surrounding rock is small,and the bearing capacity of supporting body is within the yield range,which indicates that the width of coal pillar and roadway support plan are reasonable.The research results were successfully applied in Limin Coal Mine and achieved good economic and technical benefits.The research method combined with various methods in this paper not only provides a theoretical basis for the safe and efficient mining of Limin Coal Mine,but also has certain guiding significance for the narrow coal pillar width design and surrounding rock control of gob-side roadway under similar engineering geological conditions.