中文摘要：

为研究软土盾构法隧道的纵向应力松弛特性,对钱江隧道典型断面的管片体、衬砌环面的纵向应力松弛特性和环间纵向连接螺栓轴力的时变特性进行了长达两年的现场实测。结果表明,软土盾构法隧道管片体的纵向应力松弛将经历周期性剧烈波动、动态稳定、逐渐衰减、趋于稳定四个阶段的演变,其纵向应力平均值由3 MPa逐渐松弛为1.2MPa,在达到稳定前至少需要1 a时间;与此同时,衬砌环缝面上的接触应力松弛也经历上述4个阶段的演变,其接触应力平均值由2 MPa逐渐松弛为1 MPa,在达到稳定前至少需要18个月;隧道环间连接螺栓轴力先减小、然后暂时稳定、最后增大,且在经历了2 a的显著波动后仍未稳定表明隧道纵向应力松弛导致接触状态仍处于复杂的演变过程之中,其最终稳定需要更长时间。软土盾构法隧道的纵向应力松弛是衬砌环间接触调整、土体–隧道结构接触调整和螺栓体松弛三大要素的时变性及其共同作用的结果,可导致隧道环面接缝刚度降低、环间抗剪承载力下降、环间接缝的防水密封性能弱化等,应引起工程界重视。

英文摘要：

In order to study the longitudinal stress relaxation properties along shield tunnels in soft ground, two years of field tests in Qianjiang Tunnel are carried out using monitoring cells to obtain the relaxation characteristics of tunnel segments and the contact surface between adjacent lining rings, and to obtain the time-dependent response of longitudinal bolts connected adjacent rings. The results show that the longitudinal stress evolution process inside the segments in soft ground experiences four stages： drastic fluctuation, dynamic stabilization, gradual attenuation and final stabilization. The longitudinal stress relaxation inside the segments lasts for at least 1 year, and causes stress reduction from 3 to 1.2 MPa gradually. Similarly, the development of longitudinal stress between adjacent lining rings experiences four periods as well. After 18 months of longitudinal stress relaxation, the stress value on the interface between adjacent rings decreases from 2 to 1 MPa. The axial forces of bolts decrease first, then temporarily stabilize, and finally increase, and the axial forces of longitudinal bolts are still not stable after two years of dynamic adjustment. Therefore, the origination of longitudinal stress relaxation along the shield tunnel in soft ground is the time-dependent response of contact adjusting between adjacent rings, interaction of lining and soils, and axial forces relaxation of bolts, and conpled-interaction with each other. The stress relaxation along shield tunnel will easily lead to stiffness degradation, shear resistance reduction, and leakage water, etc. The above characteristics should be considered carefully in the future.