盾构隧道足尺试验装配式加载平台的设计与应用

Design and Application of a Prefabricated Loading Platform for Full-scale Shield Tunnel Test

运营盾构隧道常受到附近地面堆载、基坑开挖和打桩等近接施工因素的影响,在外界复杂荷载的作用下盾构隧道结构原有的受力平衡会被打破,可能导致结构变形超标或破损。为准确判断隧道结构在复杂荷载作用下的适用性,开展足尺试验是研究隧道结构力学性能和破坏特征最直接而有效的手段。为了拓展盾构隧道足尺试验的适用性,提出适用于不同断面盾构隧道结构足尺试验的装配式钢结构反力架。在水平方向上通过不同标准单元的组合以及法兰式的节点连接可以提升反力架在不同断面和不同尺寸结构试验中的适用性;在竖直方向上采用嵌套式立柱连接可以有效实现各层反力架的连接和剪力的传递。设计4种加载工况对反力架整体受力和节点强度进行验算,并进一步通过圆形盾构隧道的原型结构加载试验验证该装配式加载平台的可行性。

Operational shield tunnels are often affected by nearby surface loads,excavation of foundation pits,and piling activities.The external complex loads acting on the shield tunnel can disrupt the original force balance of the structure,potentially leading to excessive deformation or damage.Conducting full-scale tests is the most direct and effective means of studying the mechanical performance and failure characteristics of tunnel structures under complex loads to accurately assess the applicability of tunnel structures.To expand the applicability of full-scale tests for shield tunnels,a prefabricated steel reaction frame suitable for full-scale tests of shield tunnel structures with different sections has been proposed.The horizontal applicability of the reaction frame for different sections and sizes of structural tests is achieved through the combination of different standard units and flange-type node connections.In the vertical direction,nested column connections are adopted to effectively solve the connection and shear transfer between layers of the reaction frame.Meanwhile,the overall stress and node strength of the reaction frame were checked against four extreme loading conditions,and the feasibility of this prefabricated loading platform was further verified through the prototype structure loading test of a circular shield tunnel.