| Wangjialing Coal Mine's fully mechanized caving face has a large roadway section.Due to multiple influences such as excavation disturbance,adjacent fully mechanized caving face mining disturbance,and mining disturbance of the current face,roof coal cracks,step sinking,large-area net pockets,and anchor cable failure have occurred.Broken and deformed sides,failure of anchor rods,bulging and cracking of bottom plate,and even roof fall,etc.,affecting normal production.Based on field investigations and laboratory experiments,this thesis first analyzes the structural characteristics of the overlying strata of the strong mining coal roadway,and determines the reasonable coal pillar width through theoretical calculations and numerical simulations.It is proposed to adopt asymmetric "multi-anchor cable-groove" The “Steel” support form supports the surrounding rock of the roadway and determines the support plan;finally,the support plan is tested and observed to verify the coal pillar width and the reliability of the support plan.The main results of this thesis are as follows:(1)Through statistical analysis of experimental data,the physical and mechanical parameters of 2# coal are obtained: coal compressive strength c=13.33 MPa,cohesive force c=2.48 MPa,internal friction coefficient tan?=0.895,internal friction angle ? =41.78 °,resistance Tensile strength ? t=1.034MPa;roadway roof rock compressive strength c=59.70 MPa,cohesion c=6.2MPa,internal friction coefficient tan?=1.1185,internal friction angle ?=48.20°,tensile strength?t=7.969 MPa.(2)By analyzing the surrounding rock structure of a fully mechanized coal roadway under strong mining,theoretical calculations show that the key rock block B is fractured at 6m within the coal pillar;the ultimate strength calculation method is used to calculate the section coal pillar width under strong mining conditions,Theoretically obtain a reasonable coal pillar size of 7.67m;establish a three-dimensional numerical model of fully mechanized caving face,use the second and third invariants of deviator stress,analyze the deviator stress field and data curve distribution law under different coal pillar widths,Determine the reasonable narrow coal pillar width is 8m.(3)The high prestressed cable anchor truss system and supporting principle are analyzed,and the asymmetric "multi-anchor Cable-channel steel" support form is proposed to support the surrounding rock of the roadway.With the aid of numerical simulation software,the relationship between the deformation characteristics of the roadway surrounding rock and the depth of the plastic failure zone of the roadway surrounding rock and the relationship between the length of the anchor cable,the span of the anchor cable truss and the eccentricity of the anchor cable truss are analyzed,and the following support parameters are obtained:(1)The anchor cable truss system can better control the deformation of the two sides and the roof when the eccentricity is 400mm;(2)When the anchor cable length is 8m,it can better control the deformation of the roadway surrounding rock;(3)The anchor cable spacing in the anchor cable truss system is 1.6m At this time,it can fully its lateral resistance effect,and the supporting effect is the best at this time.(4)According to the above-mentioned data,design the 12109 return airway support plan and conduct tests and field observations.The maximum sinking amount of the roof is 97 mm and the maximum deformation of the two sides is 138 mm through on-site measurement.No obvious separation of the roof is found.In terms of stress,the stress concentration coefficient of the two sides increases slowly with the advancement of the working face.The rock deformation shows obvious asymmetry along both sides of the central axis of the roadway.It is concluded that the asymmetric support of the anchor cable truss can effectively control the deformation of the surrounding rock of the roadway and solve the problem of the influence of multiple disturbances. |
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