悬索桥隧道式锚碇承载机理研究及工程应用

With the construction of highway and railway in West China, suspension bridge has been paid much attention to for its characteristics of strong spanning ability and small environmental disturbance. Anchorage is one of the main stress components of suspension bridge. In the mountains, using rock mass to support load effectively, tunnel anchorage is adopted to protect the natural environment, to avoid large-scale excavation, to save investment and so on, which is of great significance. However, due to the more restrictions of tunnel anchorage to the requirement of geological condition, the actual application is not much. Now the interaction mechanism of anchorage and surrounding rock is not very clear and the design of tunnel anchor also do not form a system. Relying on the first railroad suspension bridge of jinsha river bridge in our country, the study is to use model test method to research load transfer rule and deformation distribution characteristics of tunnel anchor, through the overload test to reveal tunnel anchor failure mode under three different contact surfaces. Based on ABAQUS to establish rock constitutive model of elastic and brittle plastic damage, through numerical analysis methods to analyze tunnel anchor rupture mechanism and influencing factors of tunnel anchor bearing performance. According to the limit equilibrium theory, to present tunnel anchor ultimate bearing capacity calculation method and design process, so as to provide the scientific basis for the reasonable design of railway tunnel anchor of suspension Bridges. The results of the study have theoretical significance and application value on promoting the application of tunnel anchorage in railway engineering and on enhancing the level of design technology.

随着祖国西部高速公路、铁路建设，悬索桥以其跨越能力强、环境扰动小的特点备受关注。在山区若能因地制宜，有效地利用岩体承载，采用隧道式锚碇对保护自然环境、避免大规模开挖、节约投资等方面意义重大。然而，由于隧道式锚碇对地质条件的要求较为苛刻，实际应用不多。人们对锚碇与围岩相互作用机理尚不十分明确，隧道锚的设计也未形成体系。本项研究结合我国拟建的首座铁路悬索桥金沙江大桥，采用模型试验的方法揭示隧道锚的荷载传递规律、变形分布特征；通过超载试验揭示三种不同接触面下隧道锚的破坏模式；基于ABAQUS建立岩体的弹脆塑性损伤本构；通过损伤数值分析方法分析隧道锚破裂机制及隧道锚承载性能影响因素；根据极限平衡理论，提出隧道锚极限承载力计算方法及设计计算流程，为铁路悬索桥隧道锚的合理设计提供科学依据。该研究成果对于促进隧道式锚碇在铁路工程中的应用，提升设计技术水平，具有理论意义和应用价值。

与重力式锚碇比较，隧道式锚碇因具有环境扰动小和性价比高的优势，而备受关注。丽香铁路金沙江大桥是我国拟建的首座铁路悬索桥，两岸均采用隧道式锚碇，由于铁路具有重载的特点，其主缆拉力远大于一般的公路桥梁，以往有关公路悬索桥的研究成果在铁路中的应用受到了一定限制，隧道式锚碇与围岩的相互作用机理尚不十分明确，隧道式锚碇还未形成较为完备的定量设计方法。本文以丽香铁路金沙江特大桥隧道式锚碇为研究对象，采用理论计算、数值分析、模型试验相结合的研究方法，对铁路悬索桥隧道式锚碇的承载机理及计算方法开展了研究。采用模型试验方法揭示了隧道锚的变形影响区特征，建立了锚碇体荷载传递曲线函数关系，推到了锚碇体与围岩界面剪应力的计算公式；通过超载试验揭示三种不同接触面下隧道锚的破坏模式；基于ABAQUS建立岩体的弹脆塑性损伤本构，同时考虑岩体的张拉-剪切复合破坏机制，较好地模拟岩石体破裂后的力学行为；为研究岩体真实的破裂过程提供了基础；通过损伤数值分析方法模拟隧道锚加载破裂全过程，分析围岩性质、锚碇体与围岩接触面强度、锚碇体扩展角、轴向长度及断面直径对隧道锚承载性能的影响；根据极限平衡理论，提出隧道锚极限承载力计算方法及设计计算流程，为铁路悬索桥隧道锚的合理设计提供科学依据。该研究成果对于促进隧道式锚碇在铁路工程中的应用，提升设计技术水平，具有理论意义和应用价值。