Heave Mechanism And Countermeasures Of Large Section Mining Roadway For Close Distance Coal Seams

Floor heave of large section minging roadway for the close distance coal seams is even more difficult to solve than others in the coal mining process. Additional stress on the lower coal seam is generated because of concentrated stress from leaved coal pillar affected by its exploitation, which results that the roadway is difficult to be maintained. Today, roadway’s cross-sectional is larger and larger, as result of high-production and high-effect.The roadway deformation and floor heave are more and more serious under the impact of mining, and the normal production of the mine is seriously affected.The stress distribution below pillar, mechanism of the floor heave, impact on heave of roadway section, and ways to treating the heaving floor were discussed in this paper with theoretical analysis, field measurement and finite elements methods. The conclusions were as follows:The stress distribution of Bulianta’s lower pillar was gotten by theoretical calculation. The farther the distance from the pillar center, the smaller the stress, or the closer,the greater the stress. At different depths in the floor, the stress gradually decay, as the depth away from pillar side increases. However the decay rate gradually slows down with the increasing depth. Stress will reduce as the distance away from the center of pillar bottom. What is more, the decay speed reaches fastest near the edge of the coal wall. The influence depth of stress is about80metres. Floor stress transmission angle is17.6°The rock beam was divided into three kinds of structures:upper and soft, upper and hard, and average type. In the role of horizontal stress, structural surface is easily damaged and composite beams of the soft rock under hard type are prone to separate by defining three groups of rock beam and bottom floor. The rock beam will no longer be a whole after separation. Bending stiffness and critical stress of single layered rock beam greatly reduced compared with the full rock so that it is easier to lose balance.So lithological case of laminated beams of rock bottom has a very important influence on the buckling. The theoretical calculation formular of heave amount was concluded according to the limit equilibrium zone. The amount of heave has a close relationship with the section of roadway. Critical stress of the roadway decreased rapidly as the roadway become wider; at the same time, the critical depth of slate beams being instable reduced. Large section roadway more vulnerable to the threat of the kick drum; kick drum linearly increase with the increase of roadway cross-section.Taking Bulianta mine kick drum for instance, the rational coal pillar width and the wrong pitch were not only studied by theoretical analysis, and numerical simulation, the three heave governance program were but also determined: reinforcing the roof and walls+floor rock bolt、reinforcing the roof and walls+reverse arch、reinforcing the roof and walls+concrete precast products+Prop. In this paper, a detailed study of a large section roadway system by heave the drum when the problem affecting close seams, got the kick drum kick drum mechanism and control program, can provide useful lessons for future similar problems.