高速铁路桥隧相连段结构设计

位于中西部山区的高速铁路需修建大量的桥隧工程,造成桥台(梁)伸入隧道内布置,隧道洞口段往往为土质地层或基岩风化层,地质条件比较差,桥隧相连段隧道断面大,结构受力复杂,设计、施工难度很大,处理不好,容易留下安全隐患。以西成客运专线工程设计为实例,采用工程类比与理论计算相结合的方法,对桥隧相连段的尺寸拟定、结构设计、排水设计方案等主要技术难点进行研究,成功解决了桥隧相连段的设计难题。研究结论:(1)隧道净空尺寸除满足建筑限界外,必需考虑桥台、梁的结构尺寸、检修高度、设备布置等综合因素;(2)桥隧相连段断面大,结构措施宁强勿弱、安全可靠;(3)隧道低洞口端要设置汇水井、转向排水管、引排管等设施,解决排水问题。

Structure Design of Junction Area between Bridge and Tunnel on High-speed Railway

There are lots of bridge and tunnel projects to be built on the high-speed railway in Midwest China mountain areas,in the form of bridge stretching into the tunnel portal.However,the geological condition at a tunnel portal is often so bad that it consists of soil texture strata or bedrock weathered strata,while the cross-section of the junction area between bridge and tunnel is quite huge with complex stress state.So it is difficult to design and construct the junction area;and if it were not treated properly,the potential safety hazard would be likely to occur on it.Taking the Xi'an-Chengdu Passenger Dedicated Line as a design example,and combining project analogy method with theoretical calculation method,the author carried out a research on the main technical problems of the junction area,such as the size selection,structure design,water drainage design scheme and so on.Eventually the author solved the design puzzle of the junction area between bridge and tunnel successfully.The research conclusions are as follows:(1) the clearance size of the tunnel should meet not only the requirement of railway clearance limit,but also the comprehensive factors,such as the structure size of the bridge abutment and girder,overhauling height,equipments layout and so on;(2) in view of the cross-section of the junction area between the bridge and tunnel is usually very large,the structural measure should be as reliable and strong as possible;(3) the devices such as water gathering well,turning drainage pipes,leading and discharge pipes should be installed near the lower tunnel portal to solve the drainage problem.