Method for secondary expanding excavation of loose body stratum lining tunnel

Abstract

The invention discloses a secondary expanding excavation method for a loose body stratum lining tunnel. The method comprises the following steps that S1, a high-speed geological radar is adopted for detecting surrounding rock in front of the tunnel needing to be expanded and excavated; s2, arranging and analyzing data adopted on site, determining the distribution condition of the loose range of the surrounding rock of the tunnel in the axial direction of the tunnel, and making a reinforcement treatment mark for a section needing to be reinforced; s3, further exploring the pilot holes in the part needing to be processed by adopting a disk drill and a hand-pneumatic drill, reserving a rock mass by more than 3.0 m after the drilling depth is deep into expanded excavation, and controlling the drilling annular spacing and row spacing of the pilot holes to be 4.0 m; the secondary expanding excavation method for the loose body stratum lining tunnel is high in supporting strength, the safety coefficient in the tunnel is greatly improved, the construction cycle operation time can be shortened, the engineering construction speed is increased, and the method is suitable for application and popularization.

Description

technical field [0001] The invention relates to the technical field of tunnel engineering construction, in particular to a method for secondary expansion and excavation of a loose body stratum lining tunnel. Background technique [0002] Tunnel expansion and excavation is to further construct the original tunnel in order to strengthen the support, optimize the tunnel waterproof and drainage system, beautify the appearance of the tunnel, and facilitate the installation of communication, lighting, monitoring and other facilities in the tunnel to meet the use requirements of modern tunnel construction. [0003] However, the traditional construction method of secondary tunnel excavation usually leads to the expansion and loosening of the stress relaxation circle of the top arch, and the loose circle of the surrounding rock of the cavern falls off during the excavation of the tunnel section, which will further increase the collapsed arch of the cavern. As a result, the initial su...

AI Technical Summary

Problems solved by technology

[0003] However, the traditional construction method of secondary expansion excavation of the tunnel usually leads to the enlargement and loosening of the stress relaxation area of ​​the top arch, and the loose area of ​​the surrounding rock of the cavern falls off during the excavation of the section of the cavern, which will further increase the collapsed arch of the cavern. As a result, the initial support steel support after the expansion was squeezed by the slag collapsed on the roof of the tunnel, resulting in subsidence and encroaching on the designed section of the second lining, resulting in a decrease in the safety factor in the tunnel and directly affecting the overall construction progress