Selection Of Location And Profile For Blind Ventilation Slope In Hongyi Coal Mine And Its Control Technology

It is inevitable for the roadway to have weak lithology structures as the surrounding rocks contain weak and soft strata. With different roadway locations and profiles, the weak lithology structures can pose various degrees of influence to the stability of the roadway, rendering various degrees of difficulties in controlling roadway surrounding rocks. Therefore, it is of great theoretical and practical significance to study the roadway containing weak lithology structures.With the blind ventilation shaft in Hongyi Coal mine as its research object, this paper carried out field investigations into the geological settings of the roadway and conducted laboratory experiments on specimens obtained from the roadway site. It is found that the surrounding rocks contain 0.9 m thick weak and soft strata. Additionally, the deformation and failure characteristics of the roadway containing weak lithology structures and its control technology were also analyzed. Based on field engineering geological condition, four roadway layout schemes are proposed. Scheme I-1: Roadway with a semicircular arch profile excavating along the roof coarse sandstone of the #5 coal seam. Scheme I-2: Roadway with a rectangular profile excavating along the roof coarse sandstone of the #5. Scheme II-1: Roadway with a semicircular arch profile excavating along the floor of the #5 coal seam. Scheme II-2: roadway with a rectangular profile excavating along the floor of the #5. Four different schemes were designed to study the effect of the location and profile on the roadway deformation and failure using numerical simulation. Results demonstrate that minor deformation and failure of the roadway occur in scheme I-2 and II-1. The scheme I-2 was determined as the optimal one among the four with the consideration of roadway stability principle and support technology. Thus, the roadway with a rectangular profile is excavated along the roof coarse sandstone of the #5 coal seam. The control measures were proposed to deal with the weak structures in the rib corners of the roadway. Additionally, the role and effect of the rock bolt and anchor cable were numerically investigated. As a result, synchronized deformation principle for the interior and exterior bearing structure is put forward. It is required that with the action of the exterior bearing structure and an unfavorable condition of the surrounding rocks the combined support consist of rock bolt and anchor cable should be adopted to form a synchronized deformation between the interior and exterior bearing structure, which proves effective in controlling roadway deformation. Numerical investigations were conducted to study the matching relation between the rock bolt and anchor cable in accordance with the characteristics of the surrounding rocks. Field applications demonstrate that after adopting the optimal scheme and using the proposed control technology the roadway deformation can be brought under effective control, which accrues favorable technological and economic benefits. This study can provide a reference to the control of roadway with similar conditions.