一种改进的盾构隧道双层衬砌分析模型及其应用研究

AN IMPROVED ANALYSIS MODEL FOR SHIELD TUNNEL WITH DOUBLE-LAYER LINING AND ITS APPLICATIONS

在分析现有3种双层衬砌数值模型的基础上,提出改进的双层衬砌盾构隧道衬砌梁–接头弹簧–结合面压杆弹簧组合分析模型。该模型采用压杆、结合面点位移耦合等技术,解决现有模型中地层与衬砌之间、双层衬砌结合面之间存在拉力以及结合面剪切应力与剪切位移无关等问题,提出适用于该模型的双层衬砌结合面和地层衬砌接触面参数计算依据,探讨结合面单元数量对分析结果的影响,研究杭长客运专线钱塘江隧道双层衬砌的力学行为。研究结果表明:(1)双层衬砌厚度增大将引起双层衬砌弯矩明显增大,其增大趋势与双层衬砌厚度增大趋势基本一致;(2)双层衬砌厚度的增大对轴力的影响甚微;(3)双层衬砌弯矩在管片衬砌和二次衬砌之间的分配比例与管片衬砌和二次衬砌的厚度相对比例无线性关系。研究结果对未来水下双层衬砌盾构隧道的设计分析具有一定的参考价值。

Based on three kinds of existing numerical models, a new analysis model with lining-segment joint-contact surface replaced by beam-spring-compression bar and spring combined element for shield tunnel with double-layer lining is improved. The problems of radial tension existing on the contact surface between strata and segment and between segment and secondary lining, and shear stress independent on shear displacement in contact surface between segment and secondary lining are solved by application of compression bar element, method of point displacement coupling, etc.. The formulas of some critical parameters are given. The influences of contact surface elements number on results are discussed. The mechanical behaviors of Qiantang River tunnel on a high speed railway from Hangzhou to Changsha are studied. The results show that： （1） The bending moment of double-layer lining increases obviously as its thickness increases, and the increasing trend of bending moment keeps basically consistent with that of double-layer lining thickness. （2） The increase of double-layer lining＇s thickness has little effect on axial force of double-layer lining. （3） There is no linear relationship between distribution proportions of bending moment on segment and secondary linings and their thickness proportions. Theresearch results have some reference value for the design and analysis of underwater double-layer lining shield tunnel in the future.