螺栓对高轴压盾构管片接头抗弯性能影响研究

在大埋深、高水压等特殊条件下进行盾构隧道管片结构设计时,具有复杂接缝面的管片接头形式得到广泛运用,为具体探究其抗弯性能以及螺栓的作用,采用有限元软件Abaqus,结合具体工程实例,建立大直径盾构隧道管片接头三维非连续接触模型,针对高轴压作用下管片接头的变形特征、抗弯性能和承载能力进行对比分析。计算结果表明:(1)对于大直径盾构隧道管片接头结构,有无螺栓工况之间极限承载弯矩的差值随着轴力的增大而逐渐减小。结构体系失稳前同一弯矩下有无螺栓工况之间的张开量差值随着轴压的减小而逐渐增大;(2)高轴压作用下管片接头接缝面混凝土压溃破坏时螺栓尚未进入屈服阶段,且随着轴力的增加,有无螺栓工况下接头抗弯刚度的相对数值差异显著减小;(3)较之有无螺栓工况,对于高轴压盾构管片接头变形特征和抗弯刚度的影响而言,两种不同等级螺栓的区别不大。总体来说,随着轴压的增加,螺栓对于管片接头的变形控制和抗弯性能提升的贡献逐渐减小。

Study on Effects of Bolts on Bending Behaviors of Segment Joints under High Axial Compression

To design a shield tunnel under special conditions such as large buried depth and high water pressure, segment joints with complex seams are widely used. To study the bending behaviors and functions of bolts, a three-dimensional discon-tinuous contact model is established with the finite element software-Abaqus based on engineering practices. The deformation features, bending behaviors and bearing capacity of segment joints under high axial compression are compared and analyzed. The results show that:(1) The splaying amount of ultimate bearing moment between bolted and non-bolted conditions decreases with the increase of the axial force while the splaying amount of the opening under the same bending moment gradually increases with the decrease of axial pressure;(2) The bolt has not yet entered the yield stage when the concrete of segment joints is crushed, and the splaying amount of flexural rigidity of segment joints decreases significantly between bolted and non-bolted conditions with the increase of axial force;(3) The comparison of cases with and without bolts shows that the splaying amount can be ignored of the two kinds of bolts with different strength level in consideration of the deforming characteristics of segment joints under high axial force and the effect of bending stiffness. As a matter of fact, the deforming control and the contribution to bending resistance towards segment joints offered by the joints gradually become smaller.