Study On Surrounding Rock Control Mechanism And Truss Anchor Cable Support System Of Thick Roof Roadway In Chang Heng Coal Mine

In order to improve the output of coal,various mines have developed thick top coal fully mechanized mining methods.Although the new method has significantly increased coal production,thick top coal tunnels have lower strength of surrounding rock and developed joints compared to ordinary tunnels with hard rock masses,making tunnel maintenance more difficult.In order to solve the problems of easy roof fall and difficult support in thick roof coal tunnels,the paper takes the 9201 working face of Changheng Coal Mine as the research background.In the early stage,relevant literature and materials at home and abroad were collected and searched,while on-site research was conducted to clarify the basic conditions for engineering research.Through analysis and research on the characteristics of rock pressure behavior in thick top coal roadway surrounding rocks,targeted key support theories were proposed,and suitable key support parameters were obtained using FLAC^3D numerical simulation software.Based on this,a tunnel surrounding rock support plan was designed,and on-site industrial tests were conducted to verify the feasibility of the support plan.The main research content of the paper is as follows:On site collection of coal and rock samples from the 9th coal seam of Changheng Coal Mine,laboratory measurement of key mechanical parameters of thick roof coal roadway coal and rock samples,and completion of basic quality grading of roof coal and rock.Establish a mechanical model for analyzing the stability of surrounding rock in thick roof coal tunnels,and obtain the structural characteristics and dominant mechanical mechanisms of deformation and failure of surrounding rock in thick roof coal tunnels.Establish a FLAC3D numerical calculation model for thick top coal roadway,obtain the evolution characteristics of surrounding rock stress and displacement fields,and provide key support parameters for thick top coal roadway.Design an overall plan for controlling the surrounding rock of the thick roof coal roadway and complete on-site industrial tests.The main conclusions are as follows:（1）The maintenance characteristics of the surrounding rock of the 9201 working face are large tunnel excavation cross-section,large top coal thickness,and strong influence from mining.（2）The rock quality of Coal Seam 9 studied is relatively hard and the rock mass is relatively broken,belonging to Class IV surrounding rock;The rock layer is composed of sandy mudstone or sandstone with lower strength.The rock mass is relatively hard,with a small amount of joints and good overall properties,and belongs to Class III surrounding rock.（3）Theoretical calculations were conducted on the roof and two sides of a thick roof coal roadway.By studying the derived formulas for the stress and deformation of the roof and surrounding rock of the roadway,key support theories that can adapt to the deformation and failure mechanism of the thick roof coal roadway were proposed:the"groove type"support structure theory,the neutral axis downward movement theory of anchor rock beams,and the reverse deflection theory of truss anchor cables.（4）The numerical simulation software was used to optimize the support plan and determine the support plan.The most suitable support plan for the air tunnel is the arrangement of anchor cables in a"2-2-2"distribution,with anchor cable parameters of 8.3m length and 10°inclination,and a layout plan of 5roof bolts and 4 side bolts;The most suitable support plan for the machine lane is to arrange anchor cables in a"3-3-3"distribution,with anchor cable parameters of 8.3m in length and 10°inclination,and a layout plan of 6 roof bolts and 4 side bolts.（5）Based on numerical simulation conclusions,corresponding support schemes were designed and industrial tests were conducted.On site mine pressure observations showed that the maximum subsidence of the air tunnel was 49mm,and the maximum displacement of the two sides was 42mm;The maximum subsidence of the machine lane is 61mm,and the maximum displacement of the two sides is 52mm,without any separation phenomenon.The maximum displacement of the surrounding rock in the test section during the mining process can be controlled within a safe range,indicating that the optimized support system is reasonable and reliable.Figure[75]table[14]reference[55]...