Development of excavation damaged zones around a rectangular roadway under mining-induced pressure.

• Mining-induced pressures cause the further expansion of excavation damaged zones. • Field monitoring of borehole stresses during mining; borehole camera observations. • Roadway geometry affects the final failure patterns of excavation damaged zones. • Progressive failure process of heterogeneous rocks was presented numerically. • The developing remote cracks aggravate the development of excavation damaged zones. This paper presents an investigation of the development of excavation damaged zones (EDZs) around a rectangular coal roadway under mining-induced pressure in a longwall mining process. Field stress monitoring at a coal mine in Shaanxi Province, China was carried out to obtain stress distribution induced by mining in the surrounding rock mass. During longwall mining, a high-stress zone with a limited scope is distributed in front of longwall face, and a relatively low-stress increment occurs near the roadway wall due to the failure of rock mass. A borehole camera was employed to clearly observe the development state of cracks in the damaged zones around the roadway to capture the characteristics of the EDZ. To investigate the rock failure process and development patterns of the EDZ under mining-induced loading conditions, three numerical simulation cases considering the heterogeneity of rock were conducted with a proposed loading mode similar to the mining-induced pressure. The results of the simulations show that the complexity of EDZ development under the proposed loading conditions involves tensile and shear failures, the development of remote cracks, and the effect of roadway geometry. The development patterns of the EDZ around the rectangular roadway show agreement with field observations. [ABSTRACT FROM AUTHOR]