重载铁路四线高墩大跨连续刚构设计研究

兴保铁路安家山河大桥为重载铁路四线桥,为跨越安家山河而设,主桥采用(80+130+80) m连续刚构,桥高达94 m。该桥面临多线、高墩、大跨等复杂问题,需对结构尺寸优化、主墩墩型比选、墩梁结合部位、中跨合龙顶力、施工阶段安全稳定性等方面开展研究。通过分析得出结论,中支点梁高采用9.2 m,跨中梁高采用4.8 m,梁部的刚度及强度均满足规范要求,整体指标较好;主墩采用空心墩与双薄壁墩组合,在保证足够刚度的前提下,有效降低刚度差;墩梁结合部位采用固结方式,节省大吨位支座及后期维修养护。经局部分析,梁体应力状态较合理;中跨合龙顶推力采用4 000 kN,改善了后期桥墩的受力及线形;主墩在梁体最大悬臂施工状态下安全性较好。

Design and Research on Four-track Continuous Rigid Frame of High-pier and Long-span of Heavy Haul Railway

Anjiashan River bridge on Xingbao Railway is a four-line bridge of heavy haul railway to cross the Anjiashan River. The main bridge is(80+130+80) m continuous rigid frame with height up to 94 m. The bridge is characterized by multiple lines, long span and high pier, and researches need to be conducted on structural measurement optimization, comparison of main pier type, pier-beam joint location, jacking force, safety and stability during construction. Analysis shows that the center fulcrum beam height is 9.2 m, the mid-span beam height is 4.8 m, the rigidity and strength of the beam meet the requirements of the code with good performance indexes. Hollow pier and double thin-wall pier are used in the main piers, which effectively reduces the difference in stiffness while ensuring sufficient stiffness. Consolidation method is adopted for pier beam joint to save large tonnage supports and maintenance at later stage. The local analysis demonstrates reasonable beam stress. 4 000 kN jacking force adopted for mid span closing has improved the stress and line form of the main piers. The main piers are safe while the main beam is constructed with the cantilever extending to the outmost.