Research on mechanism of deformation and failure for steeply inclined roadways in soft-hard alternant strata and its support technology

Aimed at solving the large deformation control problems of surrounding rock masses of steeply inclined roadway in soft-hard alternate strata, field tests, theoretical analysis and numerical simulation and other research methods were applied to analyze the mechanism of deformation and damage for steeply inclined roadway surrounding rock masses under typical condition of alternate strata. The results show the asymmetric deformation characteristic of surrounding rock of steeply inclined roadway in soft-hard alternate strata, evident effect of unsymmetrical pressure, the mutual miss movement deformation features of "roof sliding and floor heave", obvious floor heave and high possibility of wall caving and roof collapse. The deformation failure was significantly influenced by an obtuse angle region between roadway sections and incline directions of rock strata, which is less confined, ending up with more shear strain. Deformation and failure of lower wall rock mass aggravated compared to the upper wall rock mass. Based on the deformation and failure characteristics of steeply inclined roadway, according to the strategy of asymmetric coupling support, the key position of surrounding rock that may produce deformation discrepancy was reinforced by anchor cable and floor bolt after bolt-net-anchor coupling support and the large deformation of roadway was effectively controlled.