Technology Of The Retaining Roadway Along Goaf In Middle Thick Coal Seam

With coal production increasing, exceed of the gas content has become the main reason of high production and efficiency in the working plane of medium-thickness coal seam. The technology of retaining roadway along goaf is one of the most effective ways to govern high gas in the working plane. Roadway along goaf can also greatly improve the recovery rate of coal resources, to realize reciprocating mining, to reduce the mining roadway drivage rate and the moving time. This technology is superiority, and has remarkable economic benefit. In this paper, through the combination of theoretical analysis, numerical simulation and engineering practice, surrounding rock deformation and activity patterns were studied on the basis of previous analysis. The article proposes technology of surrounding rock control of retaining roadway along goaf in medium-thickness coal seam.The main research works are as follows:(1) Introducing Hou Chaojiong concept of big and small structures into surrounding rock stability study of retaining roadway along goaf in medium-thickness coal seam. Under the action of obturator and Mined-out areas’broken rock, the hard old roof which is above at the test roadway has rebalanced and formed the new structure. We called large structure of surrounding rock of roadway. The hanging action with bolts and anchor cable made the unstable roof anchor together,and this structure called the small structure of surrounding rock.(2) Through the establishment of the key block mechanics model and mechanical analysis,we concluded that:during the period of recovery of the upper and lower working face, the key block of test roadway has large rotation, but not lose its balance.So if they can maintain immediate roof stability, retaining roadway along goaf can be successfully implemented in medium-thickness coal seam.(3) Proposed obturator must both has enough initial support force and has certain contractility.Because sufficient initial support force can ensure the obturator cut off the roof at the edge of Mined-out areas. Cntractile properties can prevent obturator from damaged by upper large structure’s rotary sinking.(4) Roadside packing in medium-thickness coal seam was studied.Using methods of the numerical simulation, we analyzed the vertical displacement and stress characteristics of obturator in different widths.A reasonable width of obturator was confirmed in the end.(5) The research results of analysis and numerical calculation is used in engineering practice. Some observations of strata behavior are carried out.(6) By analyzing and summarizing the law of mining pressure of18207retaining roadway along goaf evaluated the feasibility of the retaining roadway along goaf in middle thick coal seam.