Study on the mechanism and control technology of large deformation of roadway surrounding rock in the fault fracture zone

Based on the geological condition of Changcun coal mine's N3-6 haulage drift, the mechanism of large deformation of surrounding rockin the fault fracture zone was analyzed. Results show that the large section effect of the roadwayin the fault fracture zone is remarkable. The large deformation of roadway surrounding rock is attributed to the composite mechanism includingthetectonic stress mechanism (IIA), in-situ stress mechanism (IIB) and random joint mechanism (IIIE). Within limits, as the Hoek-Brown constant, geological strength index of the rock massand uniaxial compressive strength of the rock increase, the instabilityscope of roadway surrounding rock decreases rapidly. The surrounding rockstress is approximately in direct proportion to the instability scope. Thecombinedsupporting method, i. e., "advance pre-grouting +cable anchor"was proposed to control the surrounding rock deformation in the fault fracture zone. The supporting effect of the original scheme was compared with the optimized oneusing the numerical simulation (FLAC3D). Results indicate that the plastic zoneareaof the surrounding rock in the optimized scheme is reduced by 56.9%, whilethe maximum displacement of the roof and floor decreases by 74%. In addition, the maximum displacement of roadway's sides decreases by 65.3%. The large deformation of roadway surrounding rock has been effectively controlled under the optimized scheme. Industrial test shows that the deformation of roadway surrounding rock tends to be stable after 25 d, and the displacements of two sides, top and bottom plate of the roadway are controlled within 300 mm. The supporting effect of the haulage drift can satisfy the engineering demand. © 2018, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.