Instability mechanism and the support technology of rail dip entry in high-stress soft rock

JIA Zhi-ming; KANG Quan-yu

doi:10.11799/ce201710018

Abstract：Aiming at the serious deformation and failure in high stress soft rock roadway, we took the rail dip entry in No. 14 mining area of Hongling Coal Mine as an example to study and analyze the deformation mechanism and rework control technology. According to the forms of deformation and failure in the dip entry, including roof subsidence ( roof caving) , two sides extrusion, spandrel, fracture of side wall brickwork and floor heave, physical mechanics experiment of surrounding rock and loose circles tests were carried out. The results show that, the surrounding rock contains many mudstone and sandy mudstone with low integral strength, which leads to large loose circles. Based on classification method of surrounding rock loose circle and analysis of roadway' s supporting theory, the coupling support method with "anchor bolt( anchor cable) + U steel retractable support + anchor + grouting" was put forward to rework the rail dip entry. We analyzed the stress distribution, displacement distribution and plastic zone distribution of surrounding rock under the proposed support scheme using numerical simulation. Filed test was also carried out, and the application shows that roof–to-floor convergence of roadway was less than 121mm after 100 days, two-rib convergence was less than 82mm, and the average convergence rate was less than 1. 0mm/d in the late monitoring, the rail dip entry was stabilized.