基于三维非连续接触模型的管片接头静动力特性分析

基于非线性接触理论,考虑盾构隧道结构的非连续性,模拟管片接头结构和管片衬砌与围岩及道床之间的相互作用,建立了道床-管片-围岩的三维非连续接触模型,对盾构隧道管片接头在围岩静压、列车动载作用下的受力与变形进行了深入分析。研究结果表明,围岩静压下拱顶和隧底处的纵向接头部分向内张开,两侧拱腰处的接头部分向外张开,拱顶处的封顶块与邻接块错台较大,拱腰接头受压明显,拱顶接头受压最小,各环管片拱顶处的螺栓轴力最大,隧底处的其次,拱腰处的接头螺栓轴力最小,旋转了一定拼装角度后位于拱肩上部的接头螺栓,其剪力最大；列车动载作用下管片接头的张开错台、混凝土应力以及接头螺栓的内力均在动载施加初期迅速增加,然后明显减小,而后产生波动,其中浅埋地铁隧道拱顶接头的动力响应较隧底接头明显,螺栓剪力在列车动载作用下较螺栓轴力增加的多。

Static and dynamic characteristic analysis of segment joints based on three-dimensional discontinuous contact model

Based on the nonlinear contact theory and considering the discontinuity of shield tunnel structure, a three- dimensional discontinuous contact model for track bed-segment-surrounding rocks is established by simulating the segment joints and the interaction between the segment and the surrounding rocks as well as the track bed. The mechanical and deformation properties of the segment joints under the pressure of the surrounding rocks and the action of the subway train dynamic load are analyzed in depth based on this model. The results of numerical simulations show that under the pressure of the surrounding rocks, some longitudinal joints in arch crown area and arch bottom open inwards; some joints in haunch of shield tunnel open outwards; and the dislocations between the completed blocks and the adjacent blocks in arch crown area are comparatively large. The joints in haunch are compressed obviously and those in arch crown have the minimum pressure under the pressure of the surrounding rocks. The axial forces of joint bolts in vault area are relatively the greatest, those in arch bottom come second, and those in haunch are the smallest. The shearing forces of joint bolts in the top of arch foots are also the greatest when segment ring rotates to an angle so as to complete assembly. The opens and dislocations of the segment joints, concrete stress and internal forces of joint bolts all increase rapidly at the beginning of the dynamic load, then significantly decrease, and finally are fluctuant under the action of dynamic load of subway trains. The dynamic response of joints in arch crown is more obvious than that in arch bottom for shallow buried metro tunnels. The shearing forces of joint bolts increase more than the axial forces under the action of dynamic load of subway trains.