Optimization of construction machine and technology of bolt for large squeezing deformation tunnel in soft rock

Based on the large deformation section of Muzhailing Highway Tunnel and the analysis of the relationship between rock drillability and drilling rig performance, five different types of bolt construction tools were selected to conduct field drilling tests. The results show that in large squeezing deformation tunnel of low strength carbonaceous slate, rotary drilling rig should select hydraulic drilling rig with higher rated drilling speed, and impact-rotary drilling rig should select drilling rig with higher impact frequency f; The drilling depth should be about 5 m. Once this depth is exceeded which problems such as hole collapse, sticking and low drilling efficiency can easily occur in drilling. It is suggested that self-propelled anchor rods above 5 m should be adopted. For the construction of short bolts within 5 m, the effective drilling speed of MYT-125/330 hydraulic anchor drill is about 0.8 m/min at the vault top and 0.4 m/min at the side wall of YT28 drill, and the construction effect is ideal; For the 10 m long bolts, the construction work of high-power trolley drill+self-propelled bolt is adopted. The effect can reach 10 m/30 min. The research results can provide a reference for the selection of bolt tools in large deformation tunnel. © 2020, Central South University Press. All rights reserved.