Study On Site Stability Of Goaf In Steep Inclined Coal Seam And Its Impact On Overlying Gas Pipeline

Based on the typical sections of Chashan and Chashan South steeply inclined goaf in Shaoguan section of Qianjiang-Shaoguan gas transmission pipeline,this paper mainly studies the environmental geological conditions,the calculation of surface deformation theory,.The residual deformation of goaf has different influence on the proposed pipeline when the direction of the pipeline and the angle between the coal seam are different.The main achievements of this paper are as follows:(1)By collecting data and comparing old and new topographic maps,the historical mining process,regional topography,geological structure,stratigraphic lithology,hydrogeological conditions and engineering geological conditions of Chashan Coal Mine and Chashan South Coal Mine were obtained.(2)The numerical simulation software is used to establish a model to fit the calculation results.The surface subsidence along the proposed pipeline is 3000 mm,the residual subsidence is 90 mm,and the surface X-direction along the pipeline is proposed.The residual displacement is-0.03469m;the Y direction residual displacement is-0.00831m;the Z direction residual displacement is-0.04454m;the stress diagram,settlement diagram and the deformation broken line diagram along the proposed gas pipeline are summarized.(3)On the basis of fitting the above calculation results,combined with the above parameters,the mining process of coal seams with inclination angles of 50,60,70 and 80 degrees,buried depth of 5m-15 m,15m-25 m,25m-35 m,35m-45 m and 45m-55 m in the whole area is simulated by numerical simulation method.It is concluded that when the buried depth of coal seams is different,with the same inclination angle,the mining of coal seams leads to the proposed pipeline construction.The vertical displacement increases first and then decreases,and the deformation range increases gradually.When the dip angle of the coal seam is the same and the buried depth is different,the vertical displacement of the proposed pipeline decreases gradually and the deformation range decreases gradually with the increase of dip angle.(4)Combining with the above parameters,the numerical simulation method is used to simulate the angle between the strike of the proposed gas pipeline and the strike of the coal seam in the goaf,which is 15 degrees,30 degrees,45 degrees,60 degrees,75 degrees and 90 degrees,respectively.It is concluded that the residual deformation of the goaf causes the deformation displacement of the proposed pipeline in the X and Z directions to increase first and then decrease,and with the increase of the angle,the deformation displacement in the X direction increases first and then decreases.The displacement range decreases first and then increases to be stable.