Analysis of mining roadway with large deformation of broken soft coal and research on supporting technology: A case study in Xin'an coal mine, China

The safe mining of Xin'an Coal Mine was challenging because of several problems, including the soft roadway seams, fracture development, fracturing and deformation of the incompact surrounding rock, and the unreasonable support parameters. Through the investigation of these problems and the analysis of the influence of active and passive support on the stability of the roadway combined with the theory, we proposed a new support plan and conducted field tests. The obtained results were as follows: broken surrounding rock, low degradation strength, unreasonable support parameters, and uncoupling of support and surrounding rock were the main causes of roadway deformation. To a certain extent, the passive support could prevent the damage of the surrounding rock, prevent the attenuation of the stress of the rock around the anchor point, and enhance the effect of active support. The active support could pre-support the gravity of the broken surrounding rock, improve the stress environment of the surrounding rock, and increase the self-balancing ability of the surrounding rock structure. It also could control the damage zone of surrounding rock and the expansion of the stress arch to the depth, restrict the range of rock strata that the passive support system needed to control, and play a protective role. The active-passive coupling support scheme had an amplifying effect. In this regard, the active-passive coupling support scheme of "bolt, W steel belt" + "anchor cable, anchor cable beam" + "I-steel shed" was practiced, and the relevant support parameters were determined. The scheme was implemented in the 2301 mining roadway, and the displacement convergence deformation of the two walls and the roof and floor of the roadway was monitored. It was found that the deformation of the roadway surrounding rock was effectively controlled and the scheme could ensure the stability of the roadway. The research results could provide a basis for the stability analysis of large deformation of broken soft coal of mining roadway and also a basis for the optimization of support parameters.