基于端头加固理论的盾构尺寸效应及界线研究

Study on Size Effect and Boundary of EPB TBM Based on Strata Improvement Theory

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,提出了改进的荷载等效模型。基于既有模型和改进模型,对粉质粘土、粉土、砂土及与砂卵石等四种地层进行端头加固统计计算,讨论了应力及纵向加固范围与盾构直径之间的关系,验证了端头加固的尺寸效应,给出了大小盾构的分界线。研究结果表明:直径小于10 m和大于10 m盾构隧道端头土体的纵向加固范围、最大拉应力及最大剪应力同直径的关系曲线呈现明显不同的变化特征,10 m直径可以作为大小盾构的有效分界线。对于直径大于10 m的盾构隧道,使用改进模型进行端头加固计算更科学、更符合实际,结论更可靠。基于盾构始发与到达端头加固理论提出的大小盾构尺寸界线,可为将来进一步研究类似问题提供了参考。

Based on analyzing and summarizing the limitations of existed theoretical model of EPB TBM, some existing conclusions are improved, a new improved load equivalent model of EPB TBM＇ s launching and arriving is proposed. Meanwhile, the current and new improved models have been put into use for improved calculation and statistic analysis in four typical strata, namely, the silty clay, silt, sand and sand-pebble strata. The relationships of stress and longitudinal reinforcement scopes with the diameter of EPB TBM have been discussed. Based on the statistic computation results, the size effect of strata improvement at the joint areas of EPB TBM ＇ s launching and arriving has been analyzed, the boundary of large size and small diameter EPB TBM have been proposed by the following conclusions ： the relationships of longitudinal reinforcement scopes, maximal tensile stress and shear stress with diameter of EPB TBM show obvious different characteristics when diameter of EPB TBM are smaller and bigger than 10 meters, and the 10 m diameter can be used as the effective size boundary for large size EPB TBM and small diameter EPB TBM. So, for large diameter EPB TBM tunnel engineering, especially when the diameter is lager than 10 meters, the load equivalent model will be more reasonable and suitable for actual engineering designing, the con- clusion will be more reliable.