盾构隧道双层衬砌结构三维力学分析模型及验证

在已有双层衬砌梁–弹簧模型的基础上,提出了改进的双层衬砌盾构隧道三维壳–弹簧力学分析模型。该模型采用压杆–弹簧组合方式模拟双层衬砌的结合面力学相互作用,并充分考虑了由盾构隧道管片接缝引起的结构刚度沿环、纵向分布不连续效应。依托武汉地铁8号线越江隧道工程进行建模计算分析,将计算得出的内力数据与现场实测的内力数据进行对比,两者具有一定的一致性,验证了该模型模拟双层衬砌盾构隧道结构三维力学行为的准确性和适用性。研究结果表明:(1)管片内力分布受到环缝和纵缝的影响呈现明显的不连续性,且由于地层岩性不均,管片上部与下部的弯矩亦有较大差异;(2)管片受力稳定后施作二衬,管片自身的内力量值变化较小,二衬主要受到自重作用,内力分布呈现"上小下大"分布规律,其量值与管片相比较小,在建设初期仅起到辅助承载作用。

Three-dimensional mechanical analysis model and verification of shield tunnels with double-layer linings

Based on the existing beam-spring model for double-layer lining structures, an improved three-dimensional shell-spring mechanical analysis model for double-layer lining shield tunnel is proposed. This model simulates the mechanical interaction on the interface of the double-layer linings using the compression rod-spring combination method, and fully considers the discontinuous effects of the structural stiffness along the ring and longitudinal distribution caused by the joints of the shield tunnel segments. Based on the modeling and calculation analysis of the Wuhan Metro Line 8 cross-river tunnel project, the calculated internal forces are compared with the measured ones. The comparison shows certain consistency between them, verifying the accuracy and applicability of the three-dimensional mechanical analysis model for double-layer lining shield tunnels. The results show that the distribution of the internal forces of the segment has obvious discontinuity due to the effect of the annular seam and the longitudinal seam, and due to the uneven lithology of the formation, and the bending moments of the upper and lower parts of the segment also differ greatly. If the construction of the secondary linings is performed after the stability of the segment, the internal forces of the segment itself change little, and the secondary linings are mainly affected by their own weight. The internal force distribution exhibits the distribution pattern of "small above and large below," and its magnitude is smaller than that of the segment. It only plays a supporting role in the initial stage of construction.