徐盐高铁复杂环境地区桥梁设计研究

Bridge Design in Complex Environments of Xuzhou-Yancheng HSR

徐盐高铁线路长、桥梁占比高,沿线地质、自然条件复杂。高烈度地震区简支梁桥按硬抗地震作用设计,研发了新型支座并优化支座布置和防落梁措施,编制适用的桥墩参考图;连续梁(拱)桥采用减隔震设计,具体根据场地地震参数和桥梁跨度选用减隔震支座或减隔震支座与阻尼器组合的减隔震措施。深厚软土区桥梁,按距离既有构筑物不小于150 m控制,设计较多打入桩,部分采用螺杆钻引孔或高压射水辅助施工,引孔深度小于2/3桩长,停止射水位置距桩底不小于3 m。岩溶区桥梁,根据溶洞上下基岩强度和厚度,厘清桩基计算边界条件;对于串珠状等复杂溶洞,采用超大群桩基础,不让桩基进入溶洞及其影响区。跨新洋港采用主跨312 m双塔双索面连续钢桁斜拉桥,半漂浮体系,塔墩固结、塔梁分离,斜拉索采用综合减振设计;为提高施工过程结构抗台风稳定性,结合结构抗风措施,采用边跨支架拼装、主跨单向悬拼的施工方案。为解决淮安东四线并行、相邻线同向行车问题,设计了线间距5.3 m非标简支梁,该梁所用预制架设设备只需对常规设备略加改造即可,方便施工。

Xuzhou-Yancheng HSR is a long railway line with complex geological and natural conditions,and the length of bridges accounts to a large proportion.For this railway,simply-supported girder bridge in high-intensity earthquake area was designed with hard resistance to earthquakes,for which innovative bearings were developed with optimized bearing layout and anti-beam-falling measures,and reference drawings of applicable pier were compiled.Seismic isolation design was adopted for continuous beam(arch)bridges.Seismic isolation bearings or the combination of seismic isolation bearings and dampers were selected according to site seismic parameters and bridge span.For bridges in deep soft soil areas,the distance from existing structures was controlled to not less than 150 m.More driven piles were used,and auxiliary construction methods such as pilot holes by screw drilling or high-pressure water jetting were adopted.The depth of pilot holes was less than 2/3 of the pile length,and the position where water jetting stops was not less than 3m from the pile bottom.For bridges in karst areas,the calculation boundary for pile foundation was identified according to the strength and thickness of upper and lower bedrocks of karst caves;for complex karst caves such as beaded karst caves,super-large pile group foundation was adopted to prevent pile foundation from entering karst caves and their affected areas.A 312 m continuous steel truss cable-stayed structure with double towers and double cable planes was adopted for the bridge crossing Xinyang Port,with a semi-floating system where the tower pier is consolidated while the tower and beam are separated,and a comprehensive vibration reduction design for stay cables;in order to improve the stability of the structure against typhoon during construction and in combination with the wind-resistant measures of structures,the side span support assembly and one-way cantilever assembly of main span was adopted.Considering parallel running of four railway lines at Huai’andong Railway Station and running of adjacent lines in the same direction,a non-standard simply-supported girder with a line spacing of 5.3 m was designed.A slight modification to conventional equipment was only required for precast beam erection equipment,which is convenient for construction.