Failure mechanism and safety control strategy for laminated roof of wide-span roadway

Abstract

The laminated roof of wide-span roadway is characterized by large subsidence, easy instability and difficult support. The open-off cut of #30102 working face in Nanliang coal mine is taken as an example to expound the roof failure mechanism. The roof exploration test are carried out to reveal geologic characteristics. The parametric asymmetric Voronoi block generation program is developed by Python, and the parametric modeling of laminated strata is first implemented in UDEC, then, the numerical model of roadway is established by combining the results of exploration test, microproperties calibration, tension and shear test of rockbolt, and bearing characteristics of timber. It can be concluded that the main types of joint failure are dominated by tensile through numerical calculation. The joint failure height is independent of the roadway width, and when the roadway width is greater than the limit span of the combination beam, there will be roof caving. Based on above analysis, the “rockbolt + timber” combined support technology is proposed, which can combine the roof strata and further reduce the roof span. Numerical simulation results and field application results show that this support scheme can effectively realize the safety control of the laminated roof of the wide-span roadway.