Study On Deformation And Failure Characteristics And Stability Control Of Large Dip Angle Thick Compound Roof Roadway

With the increasing intensity of coal mining, it’s getting less and less of the coal seams with better occurrence condition. So that the mining problem of coal seams under complicated geological conditions like large dip angle coal seams or extra-thick compound roof is increasingly been concerned by people. The amount of large dip angle coals occupies15%to20%of coal reserves in China, It has high mining value with the characteristics of large reserves and good quality. So the study for the stability control in deeply inclined coal seam mining roadway is significant. Combined with the instance of4105face tunnel of Yongning Mine. This paper studies the large dip angle thick compound roof rock stability control technology by using theoretical analysis, similar physical simulation, numerical simulation and practical application. The following are conclusions:(1) This paper put forward the deformation and failure reason of the large dip angle thick compound roof roadway:Due to the asymmetry of surrounding rock’s structure and lithology of large dip angle roadway, the roadway easy to appear asymmetric deformation and failure, especially in large dip angle thick compound roof roadway. The roof’s rock with the characteristics of small thickness, low intensity, development of bedding and fracture, the cohesion between rock is weakness. Moreover, the soft rock of the roof usually thick than8m, over the anchoring range of anchor, which makes it easy to separation caving of the roadway roof, and form asymmetric deformation and failure. (2) By a similar simulation of large dip angle thick compound roof roadway, the basic characteristics of the roadway’s deformation and failure are concluded by the study of different cross-sectional shape and different supporting ways:It is easy to appear asymmetric deformation and failure of trapezoidal cross-section roadway with symmetrical supporting, it damage more serious of the roadway’s left side, left corner, left roof and middle roof; but after using vertical wall round arched roadway with asymmetric supporting, the stress state of surrounding rock tends more homogenization, the phenomenon of stress concentration is significantly reduced. Compared with the trapezoidal cross-section roadway with symmetrical supporting, the vertical wall round arched roadway with asymmetric supporting have advantage in control two-sided displacement and roof displacement, the two-sided displacement has decreased40.9%, the roof displacement has decreased68%, the contraction of area has decreased43.3%, and the stability of the roadway has significantly improved.(3) By a numerical simulation of different cross-sectional shape and different supporting ways, the surrounding rock stress, deformation characteristics and rock plastic zone distribution are studied of different roadway. The results show that, under the same supporting, the vertical wall round arched roadway has smaller range, the distribution of stresses and displacements are more balanced; While after using vertical wall round arched roadway with asymmetric supporting, the distribution of stresses and displacements has been further balanced, the stability of the roadway has been further strengthened.(4) The result has been the practical application in the Yongning Mine4105working face roadway. After monitoring and analysis of the roadway’s displacements and the force of bolt and anchor to verify the stability of the roadway support structure, and achieving a good supporting effect, it provided a reference of the supporting of large dip angle thick compound roof roadway.