Classification Support Technology for Roadways in Deep Broken Soft Rock: A Case Study

This paper addresses the surrounding rock control problem of deep roadways in broken soft rock. The 21914 working face haulage roadway in the Zhangshuanglou coal mine was taken as a case study. The deformation characteristics and failure mechanisms of the roadway surrounding rock were analysed via theoretical analysis and numerical simulation. A classification support technology was proposed and then applied to the studied roadway. This study indicated that the high stresses, mining disturbances and mechanical properties of soft rock resulted in large deformations developed over long periods, leading to the destruction of the deep roadway in the soft rock. The failure depth of the upper goaf floor was 15.84 m, and the development radius of the plastic zone during roadway excavation was 9.55 m. The roadway deformation was positively correlated with the thickness of the interbedded fractured coal and negatively correlated with the thickness of the fractured sandy mudstone. This paper proposed a classification support technology with the main steps of surrounding rock status identification, parameter determination and graded support; the chief support measures were the addition of grout, bolts, anchor cables, steel strips, steel beams and trapezoidal sheds. The field work showed that classification support could effectively restrain the large deformation of the surrounding rock. This research can provide a reference for the stability control of other roadways under similar conditions.