Research on key control technology of surrounding rock in high stress roadway

Coal roadway in deep buried depth with high stress conditions has many difficult support problems, such as overall rib deformation, anchor bolt shear fracture, which seriously restricts the continuation of mining and tunneling, and affects the safe and efficient mining. Taking the Level-II west wing return-airroadway of Chengjiao Mine as the engineering background, the evolution law of surrounding rock fissures of the roadway is observed by YTJ-20 type on-site rock formation detector, the design of slight-trapezoidal shape roadway is proposed by mechanics model analyses theoretical of slight-trapezoidal shapeand rectangular shape, FLAC3D software is used to simulate the plastic zone evolution and deformation characteristics in surrounding rock under different ground stress conditions.The results show that: the surrounding rock has alarge-loose circle of rock, including large deformation range, fast initial deformation, long deformation duration and difficultyin supporting, high geo-stress is the main reason for the deformation and failure of the surrounding rock.The stress structure analysis shows that the force of the micro-trapezoidal shape has a relatively lower stress, which is beneficial to increase the impact resistance for the roadway, and also has a better surrounding rock control effect.The slight-trapezoidal shape has a relatively lower stress, which is beneficial to increase the anti-shock resistance for the roadway, and also has a better surrounding rock control effect. The roadway in slight-trapezoidal shape has a lower stress concentration, plastic zone and deformation than rectangle shape, especially the displacement of the side was significantly reduced, which is helpful for the stability control of the deep buried roadway with high geo-stress. The optimized shape design and reasonable support technology are the key to realize the effective control of surrounding rock deformation in high geo-stress coal roadway.Combined with the surrounding rock conditions of high stress coal roadway, the reasonable support parameters were determined based on suspension theory and numerical simulation. The tracking monitoring results show that the roof sinking reaches 20 mm and tends to be stable, two rib deformation reaches 82 mm, and floor heave is 126 mm, indicating that the deep well high stress coal roadway is designed as a micro-trapezoidal section, the roof plate adopts the anchor net belt + anchor cable beam joint support scheme, and the rib is supported by anchor net belt support. The rock control effect is good and can meet the long-term stability requirements of coal roadway.