大断面异形盾构衬砌结构纵向力学性能

首先通过建立异形盾构三维有限元计算模型研究了多种因素对异形盾构纵向力学性能的影响,数值结果表明,异形盾构纵向整体向下位移、变形模式符合三次多项式形式;纵向刚度有效率随横向刚度有效率的增加先减小后增大,但纵向刚度受横向刚度的影响较小,异形盾构横向刚度有效率设计建议值为0.65;纵向刚度有效率随埋深增加而减小,错缝拼装能明显提高异形盾构的纵向刚度;纵向刚度有效率随基床系数的增加呈线性增长,其对异形盾构纵向刚度的影响最为明显;纵向螺栓预紧力对纵向刚度有效率的影响呈线性增加关系,但对异形盾构纵向刚度的影响并不明显.基于实测环缝张开量值建立了适用于异形盾构的纵向等效刚度和纵向刚度有效率简化解析模型,解析模型计算结果与数值计算结果吻合,证明该理论模型的有效性.

Study on the Longitudinal Mechanical Behavior of Large Shield Lining Structure with a Special-shaped Cross-section

A 3D finite element model has been established to investigate the influences of various factors on the longitudinal mechanical behavior of special shaped shield tunnel structure comprehensively. The results show that: the overall displacement along the longitudinal direction of special shaped shield tunnel is downward, and the displacement curve can be represented by a cubic polynomial; the longitudinal effective rigidity ratio initially decreases and then increases with the magnitude of the transverse effective rigidity ratio; the effect of transverse effective rigidity ratio on the longitudinal stiffness is minor, and the recommended design value is 0.65; the longitudinal effective rigidity ratio decreases with the increasing depth under both staggered joint assembling and straight joint assembling conditions; the longitudinal reinforcing effect leads to a larger longitudinal stiffness for staggered jointed structure than that for straight jointed structure in soft ground; the coefficient of subgrade reaction has the most evident impact on the longitudinal effective rigidity ratio, which increases linearly with the growth of the coefficient of subgrade reaction; the amount of the longitudinal pre tightening stress of bolts also leads to a linear increasing trend of the longitudinal effective rigidity ratio, but the impact is not obvious. Finally, a simplified analytical model based on the measured value of the opening amount of the ring seam has been proposed to determine the longitudinal equivalent rigidity and the longitudinal effective rigidity ratios. The effectiveness of the model has been verified by comparing the predicted values with results of the numerical calculations.