On the basis of the stress distribution of coal-body edge and the bolting strength enhancement theory of surrounding rock, this paper elaborates the bolt-support mechanism of roadway driven along goal in fully-mechanized top coal caving face, when the less than 5m narrow coal pillar is remained. The supporting of high-strength and big-percentage elongation bolt bonded with resin grout can increase the residual strength of rock, and maintain this kind roadway. Ended with an engineering instance, a new kind of successful supporting technique is put forward.
In china, the supporting technology of the road driven along next goal in middle-thick coal seam has become a mature technology. As far as the thick coal seam is concerned, the top gate for fully-mechanized top coal caving face usually retains a barrier for supporting roadway. With increasing of the mining depth, it is still difficult to keep the stability of roadway by retaining a barrier with the width of 10?'-
The theory research imply that the bolting support can improve the peak strength and the residual strength of surrounding rock, as well as the capacity of bearing load. The stability of the road driven along next goaf in fully-mechanized top coal caving face can be realized when the narrow pillar is designed and the bolting is adopted. Obviously it is superior to the ones supported by barrier or framed timber. On the basis of the stress distribution of coal-body edge and the bolting strength enhancement theory of surrounding rock, the bolting mechanism of roadway driven along goaf in fully-mechanized top coal caving face is analyzed here.
1 The stress distribution of surrounding rock of
roadway driven along next goal In caving method, the big mining width results in the facts that the gob can't be filled with the waste; main roof will rotating-submerge and break off on the edge of the gob; the bearing stress transfer to the coal body. During this procedure, the edge of coal-body is destroyed and a fracture zone is formed with a certain thickness. At the same time, the decreasing stress zone is formed on the edge of the coal-body within a certain range(usually 0 ? 7 meters). Usually, the crossheading is driven along the floor. With a small strength, the roof is coal seam, in which the parting softens the integrity of the top coal and tempt the breakage of the top coal. Under the condition of retaining the small pillar and driving roadway along the goal, the surrounding rock, which crushed by the action of the lateral abutment pressure of the gob, has a small load-carrying ability. Because of the small stress, it is easy to maintain the roadway before the affection of the preceding abutment pressure of the face. But the affection of the preceding and lateral abutment pressure will insult in the facts that the pillar is compressed and crushed. The roof is cracked once again; the crush zone and the plastic zone are developed rapidly. The load-carrying ability of surrounding rock, above all the small pillar, is decreased faster than before, so the pressure and deformation of roadway increase rapidly. It is difficult to maintain the roadway driven along the goal in fully-mechanized top caving face in the period in which the roadway is affected by the preceding abutment stress of coal face.