为解决盾构隧道过度椭圆化变形导致的隧道结构耐久性下降和地铁运营安全风险升高难题，采用盾构隧道内部加载试验平台进行隧道内压加载变形修复原位试验研究，对不同埋深下隧道结构的力学响应特征进行分析。试验结果表明： 1）竖向内压加载对横椭圆化变形盾构隧道有较好的变形修复效果，埋深3 m时，内压加载至550 kN隧道椭圆度恢复至6‰； 埋深5 m时，内压加载至1 330 kN隧道椭圆度恢复至6‰，横向变形恢复速率显著低于竖向。2）内压加载至1 000 kN时，相较于埋深3 m工况，埋深5 m工况接缝张开恢复量减小75%，相应位置螺栓轴力和管片表面应变变化幅度分别降低88.6%和53.3%，变形修复效率降低68.9%； 埋深越大，隧道变形恢复程度越小，修复效率越低。3）内压加载变形修复过程中，拱顶区域螺栓轴力和表面应变的变化幅度最大，螺栓轴力变化幅度较管片表面应变高33.3%，隧道结构受力主要由螺栓承担，管片主要发生刚体位移；管片拱顶区域轴力逐渐减小，弯矩逐渐增大，标准块B1（135°）和K块（243°）位置附近轴力逐渐增大，弯矩逐渐减小，管片拱顶轴力与弯矩的变化幅度最大，轴力变化幅度较弯矩高11.7%，轴力重分布相较于弯矩对隧道几何形态的恢复起主导作用。
Excessive ovalization deformation of shield tunnels causes reduced structural durability and increased operational safety risks. To address this challenge, an insitu experimental study is conducted on tunnel deformation repair induced by internal pressure loading using the internal loading test platform for shield tunnels. The mechanical response characteristics of the tunnel structure under different burial depths are systematically analyzed. The experimental results show the following: (1) Vertical internal pressure loading exhibits a favorable deformation repair effect on shield tunnels with transverse ovalization deformation. At a burial depth of 3 m, an internal pressure of 550 kN restores the tunnel ovality to 6‰; at a burial depth of 5 m, an internal pressure of 1 330 kN achieves the same level of recovery (6‰). The recovery rate of transverse deformation is significantly lower than that of vertical deformation. (2) When the internal pressure reaches 1 000 kN, compared with the 3 m burial-depth condition, the 5 m burial-depth condition exhibited a maximum reduction of 75% in joint-opening recovery, while the variation amplitudes of bolt axial force and segment surface strain at the corresponding locations decrease by 88.6% and 53.3%, and a 68.9% decline in deformation-repair efficiency. These results demonstrate that greater burial depth leads to a lower degree of tunnel deformation recovery and lower repair efficiency. (3) During the repair process, the bolt axial force and surface strain at the crown show the largest variation amplitudes, with the amplitude of bolt axial force change being 33.3% higher than that of segment surface strain change. The structural load is primarily carried by the bolts, while the segments mainly undego rigid-body displacement. In the crown region, the axial force gradually decreases and the bending moment increases, whereas near the standard block B1 (135°) and the key block K (243°), the axial force gradually increases and the bending moment decreases. The axial force and bending moment variations are most pronounced at the crown, with the amplitude of axial-force change being 11.7% higher than that of bending-moment change. This indicates that axial-force redistribution plays a dominant role over bending-moment adjustment in restoring the geometric shape of the tunnel.
