大深度超大直径盾构盾尾受力性能探究

考虑盾尾壳体的初始几何缺陷及中空层合板构造,对超大直径(D14.0 m)盾构的盾尾在大深度水土压力下的力学性能进行建模分析。分别建立理想圆壳、缺陷圆壳、理想层合板和缺陷层合板4种结构分析模型,基于有限元计算,对4种模型的结果进行分析。对比发现:缺陷层合板模型在极限承载情况下最大变形为18.8 mm,最大等效应力达304 MPa,远超过理想圆壳模型的最大变形(3.6 mm)和最大等效应力(71.6 MPa),说明盾尾局部区域已发生塑性变形。因此,在超大直径盾构的盾尾设计时应考虑初始几何缺陷和中空层合板构造对盾尾变形和应力的放大效应。

Mechanical Property Analysis of Super-large-diameter Shield Tailskin under Deep Ground Load

This paper analyses the deformation and stress of super-large-diameter shield tailskin.To study the effects of initial geometrical defects and the hollow-layered shell formation on the mechanical properties of tailskin,four kinds of structure analysis models are formed:the perfect cylindrical shell model,the defeated cylindrical shell model,the perfect hollow-layered shell model,the defeated hollow-layered shell model.By FEM modelling,the defeated Hollow-layered shell model gets a maximum deformation of 18.8 mm and a maximum Mises-stress of 304 MPa under ultimate load condition,which indicates plastic deformation;while the perfect cylindrical shell model shows a corresponding result of 3.6 mm and 71.6 MPa.The study shows initial geometrical defects and hollow-layered shell formation lead to much larger deformation and higher stress level,comparing with the perfect cylindrical shell model.It is quiet necessary to consider these two factors when designing super-large-diameter shield for deep-buried tunnels.