考虑尺寸效应的盾构始发与到达端头加固研究

Reinforcement Study of the Size Effect on Departure and Arrival of the Shield Tunneling

分析和总结了既有端头加固模型的不足,针对其局限性,考虑尺寸效应对盾构始发与到达端头加固的影响,建立了适用于大直径盾构端头加固计算的荷载等效模型,将侧向梯形荷载等效为均布荷载和三角形反对称荷载的叠加。同时,应用既有模型和荷载等效模型对典型的黏土与砂土地层进行端头加固计算,分别讨论了应力及纵向加固范围与盾构直径之间的关系,分析了尺寸效应对端头加固的影响。研究结果表明,当盾构直径小于等于10 m时,两种模型应力及纵向加固范围变化曲线几乎重合,既有模型的误差较小;当盾构直径大于10 m时,既有模型的应力和纵向加固范围明显小于荷载等效模型,且随着直径的增大,两者的差值不断增大。因此,对于直径大于10 m的盾构隧道,使用荷载等效模型进行端头加固计算更科学、更符合实际,结论更可靠。而且基于盾构始发与到达端头加固理论提出了大小盾构的分界点,为将来进一步研究类似问题提供了参考。

After analyzing and summarizing the limitations improved, and a new load equivalent model suitable of existed theoretical model, some existing conclusions are for reinforcement calculation of large diameter TBM＇S commencement and arrival is presented, and lateral trapezoidal load applied in improved strata is equivalent to superposition of uniformly load and triangle anti-symmetry load. Meanwhile, in order to certify the size effect of strata reinforcement, two models have been put into use for actual engineering strata reinforcement calculation, and results are used to analyze the relationships between stress, longitudinal reinforcement scopes and the diameter of TBM, and relationships have been made followed by the conclusions ： When the diameter of shield tunnel is less or equal to 10 m, the deviation of stress and longitudinal of two models are small, but as the diameter of shield tunnel is continuously increasing, the deviation of existed model is bigger, which may cause serious accidents if applied into actual engineering. So, for large diameter shield tunnel engineering, especially when the diameter is lager than 10 meters, the load equivalent model will be more scientifically and suitable for actual engineering designing, the conclusion will be more reliable. What＇s more, strata reinforcement theory presented in this paper gives a boundary for distinguishing large and small diameter TBM, and it also provides a good reference for similar problem.