为修复因盾构接收突发涌水涌砂导致的双线隧道受损工程，采取双线隧道分离式布孔、同期冻结的修复方案，即一期垂直冻结明挖+二期水平冻结暗挖。针对2期工程中垂直钻孔、暗挖对接隧道等施工重难点，提出关键工艺： 1）垂直钻孔时采取先隧道外加固再钻孔施工，先金刚石钻头钻孔取芯再改为回转式钻进泥浆护壁的方法； 2）暗挖时破损管片区和完好管片区采用2种开挖方式，对破损管片区采取全断面开挖，对完好管片区采取先开挖至封堵墙再拆除管片的方法。然后，对2期冻结全过程进行温度、变形监测，分析冻结温度场发展规律以及地表和建筑物沉降变化规律，并与常规洞门冻结工程对比。结果表明： 1）冻土区与渗漏处热交换对测点冻结效果的影响大于冻结孔偏斜的影响； 2）在扰动地层左右线同期水平冻结时,左右线相邻冻结管处易发生冻结管断裂现象； 3）地层扰动大的修复工程中，水平冻结积极冻结期较长； 4）因回填土松散且有空洞，水平冻结钻孔施工阶段的地表沉降大于暗挖阶段。
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.
