DESIGNAND OPTIMIZATION OF THE SCHEME OF ROOF CUTTING AND PRESSURE RELIEF TO KEEPROADWAY ALONG GOAF IN MEDIUM AND THICK COAL

摘要

The technology of cutting the roof to relieve pressure and staying along the goaf is an important technology to realize pillarless coal mining at present. However, inappropriate design will not only cause damage to the ecological environment such as ground subsidence, but also waste of coal resources. Not only that,the damage caused by ground subsidence and other damages will seriously affect the local natural environment and threaten the local ecology.For this reason, in this paper, we propose a design and optimization plan for cutting the top of the medium-thick coal seam to relieve the pressure and keep the roadway along the goaf. Studies have shown that the length and diameter of the supporting bolts before mining should be designed to be 1.85 m and 20 mm, respectively, and the number of bolts in each row should be designed to be 5. In addition, the length, row spacing,and number of anchor cables in each row for roadway support should be designed to be 8.0 m, 2.25 m, and 3, respectively. During the design process of cutting pressure relief operation, it is found that the deformation of the roof will increase with the increase of the cutting roof height. By comprehensively considering the factors of safety production and coal mining efficiency. it is reasonable to design the cuttingroof height to 6.0 m. The roof cutting angle has no significant influence on the height of the stress concentration area from the top of the roadway, but it has a more severe influence on the roof displacement. Considering the effect of top-cutting and pressure-relief and the influence on the displacement and deformation of the top plate, the top-cutting angle of the top plate was designed to be 20°. This research can provide technical support for the coal mine's top-cutting and pressure-reliefoperation along the goaf and roadway retention.