敞开式TBM施工铁路隧道仰拱预制块关键设计参数研究

以敞开式TBM施工特长铁路隧道仰拱预制块结构为研究背景,基于荷载结构设计理论,采用有限元软件ANSYS构建二维平面分析模型,研究了仰拱预制块圆心角、中心水沟沟槽深度、宽度等参数对衬砌结构变形、受力特性的影响规律。研究结果表明:圆心角对仰拱预制块变形、内力影响较小,设计中应根据仰拱预制块拼装技术及轨道结构要求来确定;中心水沟沟槽底至仰拱预制块底部间距h对仰拱预制块变形、内力影响较大,设计中间距h应大于复合式衬砌厚度;扩大中心水沟宽度,可有效降低集中应力值,在满足轨上结构承载能力的前提下,设计中可适当扩大中心水沟宽度来增大隧道排水能力。

Study on Key Design Parameters of Prefabricated Invert Segment for Open Type TBM Railway Tunnel Construction

Based on the load structure design method,a calculation model of tunnel is established with the finite element software ANSYS to study the effects on the deformation and the internal force of the lining structure generated by such parameters as the central angle,the depth and width of the center ditch of the prefabricated invert segment. The results show that the central angle has less effect on the deformation and internal force of the prefabricated invert segment,and the central angle is determined by the technical requirements for segment erection and the track structure. And the distance between the bottom of the central ditch and the bottom of the prefabricated invert segment has bigger effect on the deformation and internal force of the prefabricated invert segment,so the design distance should be greater than the thickness of the composite lining structure. The stress concentration can be reduced by expanding the width of the central ditch. On the basis of the requirement for track structure bearing capacity,the drainage capacity of the tunnel can be increased by expanding properly the width of the central ditch in design.