Research On The Stability Theory And Control Of Roadway Surrounding Rock In Tectonic Stress Field

Tectonic stress which includes residual tectonic stress of the geological history and current tectonic stress, is the stress induced by the tectonic movement of the lithosphere in rock masses. Tectonic stress field is summation of the stress state in different place which is induced by all kinds of tectonic trace with genetic relation.Tectonic stress field gives priority to the horizontal stress. The biggest and smallest horizontal stress usually vary with the depth linearly. The value of the tectonic stress which inclines to hydrostatic stress when going to the deep of the lithosphere, distributes rather dispersedly in the range of the coal mining depth, but its direction is obvious.The dissertation adopts the theoretical model of the generalized strain plane problem, numerical simulation of the FLAC3d and a great deal of local measure data to study the the roadway disposal in the tectonic stress field. The research indicates that the stability of the roadway connects nearly with the disposal direction of the roadway. Fragmentation zone range of the surrounding rock becomes larger with augmentation of the angleαbetween axes direction of the roadway and the biggest tectonic stress direction. Stress and displacement in the surrounding rock varies with sin 2α. The angleαinfluences to the stability of the roadway is as follow: the range ofα=0～15°is the little effect zone, the range ofα=15°～75°is the increasing effect zone, the range ofα=15°～75°is the great effect zone. The roadway is most stable whenα=0, while least stable whenα=90°. The measurement in Yanzhou and Shenhuo mining area approved that direction of the tectonic stress influenced obviously to the disposal of the roadway.The dissertation adopts the elastopastic theory, numerical simulation of the FLAC2d and local measure to study the the roadway stability in the tectonic stress field. The research indicates that tectonic stress non-harmoniously influences to the stability of the roadway surrounding rock. The range of plastic zone in the roof and floor of the roadway increases with the augmentation of horizontal tectonic stress, especially in the shoulder of the roadway. While The range of plastic zone in the sides of the roadway decreases with the augmentation of horizontal tectonic stress. The range of plastic zone in surrounding rock of the roadway enlarges rapidly when the lateral pressure coefficientλis bigger than the ultimate value which increases with the augmentation of surrounding rock strength, decreases with the minishment of the depth.The dissertation adopts the similarity simulation to simulate the bolt supporting coal roadway in the tectonic stress field. The results indicates that horizontal tectonic stress induces slippage and bed separation between the terranes in the roof and floor of the roadway, therefore, the anti-shearing capacity of the terrane falls to cause the terrane of the roof and floor to shear failure, which cause the roof bolt to lose supporting function, and then the roof terrane falls to arch gradually. Coal mass of the sides moves collectively to the roadway space, which cause obvious displacement between the coal seam and terrane of roof and floor. Sides bolts is mostly subjected to tensile function that control the plastic deformation of the coal or rock mass. Roof bolts is mostly subjected to shearing function that control the slippage and bed separation of the roof terrane. when the roof terrane destroys, Roof bolts offer restraining force to enhance residual strength of the rock mass. The local practice approve that the roof terrane of the roadway will slip and bed separate in the effect of the tectonic stress, which causes the shear failure of the roof terran, bolt and cable.Adopting elastic theory and local measure, the reseach of the roadway under mining influence in the tectonic stress and indicates that there is horizontal and vertical tensile stress zone in the surrounding rock of the roadway near the working face. The range of the tensile stress zone increases with the increase of the ratio between the height of the caving zone and periodic weighting step, with the increase of the ratio between the horizontal tectonic stress and vertical stress. The surface displacement of the roadway under mining influence augments remarkably, thus reinforce method of the unloading rock mass must be adopted to control the surrounding rock, in order to enhance the stability of the roadway.The upper research results which is proved in the local practice, have great significance in guiding to the roadway disposal and control of the surrounding rock in the high tectonic stress zone.There are 89 figures, 26 tables and 147 references including 26 foreign literature in the dissertation.