Study On Stability Analysis And Control Technology Of Surrounding Rock In Deeply Inclined Coal Seam Roadway

Coal is one of the main energy sources in China,and the reserves of that with coal seam dip angle above 35 degrees occupy about 17% of total coal reserves.Due to the geological characteristics of deeply inclined coal seam,the stability control of roadway surrounding rock is very difficult,which is the main reason to restrict the exploitation of coal resources.In this thesis,the method of theoretical analysis,numerical simulation,laboratory test and field test are used to study the stability and control technology of surrounding rock in the roadway with deeply inclined coal seam coal seam.The main contents are as follows:(1)According to the characteristics of the roadway with large dip angle,the mechanical model for the stress-deformation analysis of roadway surrounding rock with trapezoidal cross section is established.By the conformal transformation and complex function theory,the analytical solution to the stress and deformation of surrounding rock in roadways of deeply inclined coal seam is obtained.The theoretical results show that the deformation of the high side of roadway is greater than the low side,and the deformation of roof is greater than that of the floor.The overall deformation of the surrounding rock shows the phenomenon: deformation of roadway sides > roof subsidence >floor heave.Both the maximum horizontal stress and vertical stress of the surrounding rock appear at the upper corners of the roadway,followed by the upper part of the high-side.The influence factors of roadway surrounding rock stability with large dip angle are analyzed through the numerical simulation,and the failure characteristics of surrounding rock are obtained.Comprehensive analysis shows that the high stress concentration degree and the regional characteristics of deformation and failure are obvious in the roadway with large dip angle.(2)Based on the above results,the design concept of "active-passive combined support,enhancing support strength,local reinforcement,and coordinated deformation" is proposed.In the support design,the use of anchor cables and hydraulic props combined to enhance the supporting strength,and the use of constant-resistance supports in the roadway reinforcement,while coordinating the deformation of the active and passive supporting.(3)Mechanical high-strength and constant-resistance prop for deeply inclined coal seam roadway supporting is invented,and its mechanical model under rated working resistance is established.The mechanical principle of the prop is studied,and the parameters(e.g.,the inner and outer diameter of the column,the distance of the gap,the modulus of elasticity,the compressive strength of the column,the tensile strength of the cylinder,the radius and the numbers of the steel ball)that determine the working resistance of the support are analyzed.The mechanical test shows that the load-displacement curve of the prop shows an ideal elastic-plastic constitutive relation;The prop have a strong supporting stiffness and can quickly reach the rated working resistance to support the roof;when the supports reach the working resistance,the supporting performance is stable,showing the mechanical properties of “high-strength and constant resistance”.(4)The active-passive combined supporting scheme of bolts-anchor-high strength prop for deeply inclined coal seam roadway is designed,and the numerical simulation of the supporting scheme is verified.The results show that compared with the bolt and anchor cable support,the active-passive supporting can play a good supporting role at the upper corner of the roadway,which greatly reduces the failure of the roadway.At the same time,the roadway upper corner is effectively protected which reduced the stress of the high side of the roadway,and the floor heave have also been effectively controlled.(5)The active-passive combined supporting with bolt-anchor-high strength support for deeply inclined coal seam roadway is carried out at the 5-1081 roadway of "Pang Pangta coal mine" in Shanxi province.The field test shows that the support scheme can effectively control the deformation of the roadway,especially the failure at the upper corner of the roadway.Besides,the real-time detection results of the bolts also show that the supporting scheme can reduce the stress of the bolt and achieve the coordinated deformation between the bolt(cable),supports and surrounding rock.According to the field test,the active-passive combined supporting design process for the deeply inclined coal seam roadway is finally formed.The research results of this thesis can provide a theoretical basis and method for the supporting design of deeply inclined coal seam roadway,and also can provide reference for other large section roadway supporting theory and technology research.