Field test study on large deformation control of surrounding rock of cleaved basalt tunnel

The geological structure of cleaved basalt section of Zhongyi tunnel of Lixiang Railway is complex; the surrounding rock is weak and broken; the groundwater is well developed; the ground stress is extremely high; and the side wall deformation disaster is prominent; therefor three field test researches on construction control measures for large deformation of surrounding rock have been carried out. The field test results show that: From the perspective of support reinforcement, working condition 1 and working condition 2, the deformation of the side wall of the test section has been well controlled; and the arch changing rate decreased from 100% to 38.50% and 22.22% respectively; the ringing time of the excavation section has a great influence on the control of side wall convergence and deformation; the section support after excavation of the tunnel face should be closed as soon as possible; the perspective of support and surrounding rock two-way reinforcement of the working condition 3 of "large deformation type II support + side wall with 6.5 m long anchor rod" is adopted to successfully control the large deformation disaster of the test section side wall and the arch changing rate drops to 0%. The research results can provide reference for similar projects.