关键词: 盾构隧道, 人工冻结法, 加固及修复

Abstract: The authors examine the rehabilitation of a double-track tunnel damaged by sudden gushing water and sand during shield receiving by employing a simultaneous freezing scheme in which grouting holes are separated. The open-cut Phase 1 is vertically frozen while the mined Phase 2 is horizontally frozen, halving the construction period. The primary construction techniques for vertical drilling and mined tunnel connection of the two-phase constructions include the following: (1) For vertical drilling, reinforcement is performed outside the tunnel before drilling, with core sampling achieved first using a diamond bit followed by rotary drilling with mud wall protection. (2) The mined tunnel section with damaged segments is excavated using the full-section method, whereas the intact segment is disassembled after excavating into the sealing wall. The temperature and deformation throughout the freezing process are controlled and measured, and the development of the freezing temperature field and displacement change patterns of the surface and neighboring buildings are analyzed. The results are then compared with those of conventional freezing projects. The results reveal the following: (1) The heat exchange between the frozen soil and leakage on the freezing effect is significantly greater than that of the freezing hole deviation. (2) The neighboring freezing pipes of the left and right lines are susceptible to breakage when simultaneous horizontal freezing of the left and right lines is applied in disturbed strata. (3) The active freezing period for horizontal freezing is longer in rehabilitation projects in large disturbed strata. (4) The surface settlement during the horizontal freezing stage is greater than that during the mining stage because of the presence of voids in the loose backfill soil.

Key words: shield receiving, artificial freezing method, reinforcement and rehabilitation