铁路悬索桥大吨位隧道锚承载性能分析

Analysis on Bearing Performance of Large-tonnage Tunnel-type Anchorage of Railway Suspension Bridge

丽香铁路金沙江大桥是我国首座采用大吨位隧道式锚碇的铁路悬索桥。本文采用三维弹塑性有限元方法对隧道锚的变形机理、承载能力以及围岩稳定状态进行分析。研究结果表明:在正常缆力作用下,锚碇体及周围岩体的位移均处于毫米量级,远小于悬索桥塔顶允许位移;锚碇体整体表现为以前底板为支点,锚碇体后部向上转动和整体向前滑移的变形模式;锚碇体及围岩绝大部分处于三向受压状态,只是在锚碇底端与下部围岩的接触部分,以及顶拱与边墙交界处局部范围内存在拉应力,建议在这些部位采取措施重点加强;基于超载极限分析法计算得到锚碇体的整体抗滑安全系数在9以上。有限元分析结果为铁路悬索桥隧道锚的优化设计提供了理论依据。

The Jinsha River Bridge of the Lijiang-Xianggelila Railway is the first railway suspension bridge with tunnel type anchorages of large tonnage in China. By using the three dimensional elastoplastic finite element method, the deformation mechanism ~ bearing capacity of the tunnel anchorage and the stability of surrounding rock were analyzed. The results show as follows：Under the action of normal cable forces,the displacements of the anchorage body and surrounding rock are in the millimeter range, which are far less than the allowable dis- placements of the suspension bridge tower;the deformation mode of the anchorage body includes the back part of the anchorage body turning upward with the front bottom plate as the fulcrum and the whole anchorage body sliding forward ; most parts of the anchorage body and surrounding rock are in the triaxial compression state, ex- cept that the contact surface between the bottom end of the anchorage body and the under surrounding rock and,the local boundary area between the crown hog and flank wall are subjected to tensile stresses where stressed strengthening is needed;with the overload limit analysis method, the anti-slide safety factor of the o- verall anchorage body is calculated to be larger than 9. The finite element analysis results provide a theoretical basis for optimized design of the tunnel anchorages of railway suspension bridges.