Optimized layout and excavation sequence of deep soft-rock chambers

The stability of deep soft-rock chambers is closely related to their spatial layout and excavation sequence. To optimize the spatial layout and excavation sequence of the deep soft-rock chamber group, the theoretical analysis and numerical simulation methods were used to investigate the section form, layout, and construction process of the refuge group in the context of the Wet Spraying Concrete Batching Plant (WSCB) Refuge Group at Jinchuan No.2 Mine Level 941. Firstly, the relationship between the section's shape and size and the chambers' stability was analyzed. Then, the influence of the direction of the ground stress on the layout of the chambers was considered, and the principle of the primary and secondary chambers was proposed. Finally, an analytical model was developed based on the increment of the characterization of the stability of the chambers, and the construction process was optimized. The study shows that: the optimal section shape for large section chambers is a straight wall with rounded arches; the layout of the chambers should take into account the lateral pressure coefficient and the aspect ratio of the chambers; the main chambers should be given priority; the angle between the axes of the chambers and the maximum principal stresses should be maintained at 45°~60°; the chambers should be laid out as vertically as possible; the optimal construction plan for the group of chambers is Plan Ⅰ; the chambers are arranged in the order of the batching machine chambers, followed by the mixer chambers, and the cement silo chambers, and then the cement silo chambers. The optimal excavation plan is Plan I. The chambers are excavated in the order of batcher chamber, mixer chamber, cement silo chamber and cement silo chamber. The results of this study can provide a theoretical basis for the stability control of the refuge chambers in deep mining.