水下圆砾地层盾构隧道施工期力学响应实测研究

为研究水下圆砾石地层盾构隧道施工过程中管片结构的力学响应，以常德沅江隧道为背景，选取沅江东线隧道江中埋深最大断面，采用连续测量方式对施工过程中管片的内力变化特征及管片外水压力进行测试，并将实测数据与数值模拟结果进行对比分析。主要结论如下： 1）水下圆砾地层中盾构隧道管片结构外部水压受施工过程的影响显著，距开挖面1~10环呈波动变化，沿横断面不同位置出现最大值的时间不同，但在10环之后趋于稳定； 2）管片结构轴力受到脱环和注浆的影响明显，其中前3次注浆的影响最为显著，影响范围为1~9环，弯矩变化与轴力类似，但受注浆影响较轴力延迟1环左右； 3）稳定后管片轴力和弯矩量值均大于数值计算值，说明稳定后管片受盾构顶推、浆液固结、错缝拼装效应影响较大。

In situ Tests on Mechanical Response of Underwater Shield Tunnel Segments in Round Gravel Strata during Construction Period

In order to study the mechanical response of shield tunnel segments in round gravel strata during construction period, a cross section of Yuangjiang River crossing Tunnel with the largest burial depth is selected to carry out test on internal stress variation characteristic and external water pressure of tunnel segment by continuous monitoring method, and comparison and contrast is made between monitoring data and simulation results. Main conclusions are drawn as follows: (1) The external water pressure of the segment structure is significantly affected by the construction of shield; the external pressure of ring 1 to 10 from the excavation surface fluctuates, and the time when the maximum value of different positions appears is different, which become stable after ring 10. (2) The axial force of the segment structure is mainly affected by the decoupling and grouting; the influence of the first three grouting is the most significant, and the influencing range is from ring 1 to 9; while the condition of bending moment is similar to that of axial force, but the influencing range by grouting is about 1 ring delay compared with the axial force. (3) The internal force of the segment is larger than the simulated calculation values, which indicates that the segment is affected by jacking force, hardening process of grouts and assembly effect.