大跨径悬索桥隧道锚承载力分析

基于实测综合确定的岩体参数，用三维弹塑性有限元法对包括下部公路隧道施工、隧道锚开挖、浇注、预应力施加、挂缆等全部工序进行了模拟分析．围岩和锚体混凝土离散为8节点三维实体单元，隧道和锚碇的喷射混凝土及二次衬砌离散为4节点三维壳单元．用读入初始应力法建立复杂构形的初始应力场，围岩开挖应力的释放用场变量相关折减弹性模量法模拟，用单元的激活和移除模拟锚体灌注和岩体的开挖．结果表明，设计缆力时，围岩基本处于弹性状态；数值超载时，围岩承载力约为7倍设计缆力，可能的破坏模式是两锚体向外侧歪斜拔出；剪应力最大值均出现在距后锚面约10m处；对现有锚一隧问来源，锚体破坏对下部公路隧道也无显著影响，两结构施工过程和运营阶段均能满足设计承载要求．

Support capability of tunnel-type anchorage of a long-span suspension bridge

Based on the rock mass parameters from the tests and other factors considered, the three-dimensional elasto-plastic analysis was performed to simulate the complete sequence of construction, including highway tunnel excavation, tunnel-type anchorage construction, cast in-situ, anchorage body prestressed and main cable installed, et.. The surrounding rock and concrete anchorage body were simulated by 3D brick elements with 8 nodes; the tunnel and shot concrete by 3D shell with 4 nodes; stress relax in the surrounding rock from excavation by field dependant deduct elastic modulus method; the cast in-situ concrete of anchorage body and the excavation of rock mass by active and remove of elements. Geostatic state of complex geometric structure form was built by reading in initial stress from input file. The surrounding rock is basely in elastic state under designed cable force from the results. It was seen from an numerical overloaded analysis that the capability of surrounding anchorage is times of designed cable force and the failure pattern is that two anchorage bodies are pulled out clines towards out sides. The maximum shear stress appears 10 meters before the back anchorage face. There is no obvious influence on highway tunnel during and after damage of tunnel-type anchorage in current designed distance between anchorage and tunnel. The two structures are safe during construction and traffic stages.