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针对深埋圆形隧洞TBM施工过程,综合考虑纵向推进和双层衬砌构筑过程,对围岩–衬砌进行耦合分析,得到应变软化弹塑性岩体在不同时刻施加衬砌时的应力、位移、软化区和破裂区半径的解析解,并给出带衬砌问题围岩达到软化和出现破裂的判据。推导中同时考虑了岩体在软化阶段和残余强度阶段的体积扩容。通过算例分析初衬和二衬施加时刻对围岩位移、软化区和破裂区范围以及围岩压力的影响,讨论了荷载在两层衬砌间的分担演化规律。分析表明,算例中TBM推进至3倍洞径时施加二衬,则二衬阶段产生的位移可控制在总位移的6%以内;衬砌间的作用力对二衬施加时刻较为敏感,而衬砌对围岩的支护力将受初衬和二衬施加时间的共同影响。根据提出的解答,可以进行TBM推进速度、衬砌几何和材料参数及最佳支护时机的初步设计,并预测隧洞施工中位移、应力的时程变化。
Considering the process of TBM construction in deep circular tunnels, considering the longitudinal propulsion and double lining construction process, the coupling analysis of surrounding rock and lining is carried out to get the stress, displacement and softening zone of the strain softening elastoplastic rock mass at different time And the analytic solution of the radius of the rupture zone, and gives the criterion of surrounding rock softening and rupture with the lining problem. The deduction also considers the volume expansion of rock mass in the softening and residual strength stages. By analyzing the influence of the initial lining and the second lining application time on the displacement of surrounding rock, the range of softening zone and rupture zone and the pressure of surrounding rock, the distribution and evolution of load between two linings are discussed. The analysis shows that when the TBM is advanced to 3 times of the hole diameter, the displacements of the second liner can be controlled within 6% of the total displacement. The interaction between the linings is more sensitive to the application time of the second liner, The supporting force on the surrounding rock will be affected by both the initial lining and the secondary lining. According to the proposed solution, preliminary design of TBM propulsion speed, lining geometry, material parameters and optimal support timing can be carried out and the time-history of displacement and stress in tunnel construction can be predicted.