Mechanism and technology of rock burst prevention in deep coal tunnel based on controlling surrounding rock stress difference gradient

In view of the rock burst disaster of deep coal roadway, explore the rock burst mechanism and develop the key prevention technology, based on the “Mechanism of rock burst in deep coal tunnel surroundings due to stress difference gradient” which attaches importance to the influence of horizontal stress. The stability of unit body and surrounding rock, the damage characteristics and prevention mechanism of rock burst from the perspective of stress difference are analyzed with the method of numerical simulation, theoretical analysis, on-site practice in this paper. Based on the thought of regional and local D_gc combined controlling, put forward the three-stage transformation of coal tunnel surrounding rock prevention technology program. The engineering case of 30202 working face in Muduchaideng coal mine is analyzed. The results show that: Strong rock burst propensity coal body can carry higher Δσ, in order to compensate for the excessive Δσ requires a higher intensity of energy release, Δσ drive the coal body is biased towards brittle shear rupture, Coal bodies with rock burst propensity are prone to destabilization driven by high D_gc. With the rock burst propensity increases, the D_gc value shows an increasing trend, especially in the strong rock burst propensity coal seam, high D_gc value makes the surrounding rock burst risk surge, Enhance the impedance of the D_g elevation area, weaken the D_gmax value is the focus of anti-rock explosion. Strong support in the enhancement of the strength of the coal body, but also lead to the concentration of D_g in the gang, the D_gc value is closer to the critical conditions of rock explosion. Active support and passive support and coal seam modification need combined effect to reduce the rock burst risk effectively. The first level of regional fracturing reconstruction and the second level of regional water injection modification technology can significantly reduce the Δσ value, when the rock explosion risk level of the coal body is reduced. Therefore, the spacing of drill holes in the third level can be increased appropriately. After the validation of microseismical system, pipeline pressure, coal dust volume and other indexes and practical test, this technical solution has stronger modification effect compared with traditional technical methods, and it is also more suitable for the demand of coal seam modification in high Δσ area.