城市高架桥跨地铁的大跨径承台设计
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摘要
西安某高架桥工程部分线位与地铁四号线重叠,桥梁基础为避开已建地铁隧道,需采用大跨径承台跨越。以该工程为背景,对预应力混凝土实心承台和普钢-预应力混凝土混合空心承台这两种大跨径承台分别采用有限元软件进行计算,同时对两种承台的优缺点进行对比分析,论证两种承台方案的安全性及合理性。计算表明,两种承台的强度及抗裂性能均满足规范要求,但预应力混凝土承台张拉预应力时在桩顶产生附加弯矩,对桩基影响较大,而混合承台施工期间采用分段浇筑,预应力在系梁与桩基连成整体前张拉完成,对桩基影响较小,推荐采用普钢-预应力混凝土混合空心承台。
The line positions of a viaduct project are partially overlapped with Metro Line 4 in Xian. The viaduct foundation is required to use the long-span base slabs to cross in order to keep away from the built metro tunnel. Taking this project as the background, this paper calculates these two long-span base slabs of the pre-stressed concrete solid base slab and the common steel-pre-stressed concrete composite hollow base slab, and compares and analyzes the advantages and disadvantages of these two base slabs to demonstrate the safety and rationality of these two base slab schemes. The calculation shows that the strengths and crack resistances of these two base slabs all meet the standard requirements. But the pre-stressed concrete base slab will produces the additional bending moment at the pile top when tensioned and prestrssed, which has the larger influence on the pile foundation. And the composite base slab is casted by sections during the construction and the pre-stressed tension is completed before the straining beam and the pile foundation are connected into a whole, which influence on the pile foundation is less. It is to recommend the common steel-pre-stressed concrete composite hollow base slab.
The line positions of a viaduct project are partially overlapped with Metro Line 4 in Xian. The viaduct foundation is required to use the long-span base slabs to cross in order to keep away from the built metro tunnel. Taking this project as the background, this paper calculates these two long-span base slabs of the pre-stressed concrete solid base slab and the common steel-pre-stressed concrete composite hollow base slab, and compares and analyzes the advantages and disadvantages of these two base slabs to demonstrate the safety and rationality of these two base slab schemes. The calculation shows that the strengths and crack resistances of these two base slabs all meet the standard requirements. But the pre-stressed concrete base slab will produces the additional bending moment at the pile top when tensioned and prestrssed, which has the larger influence on the pile foundation. And the composite base slab is casted by sections during the construction and the pre-stressed tension is completed before the straining beam and the pile foundation are connected into a whole, which influence on the pile foundation is less. It is to recommend the common steel-pre-stressed concrete composite hollow base slab.
引文
[1] JTG D60—2015,公路桥涵设计通用规范[S].
[2] JTG 3362—2018,公路钢筋混凝土及预应力混凝土桥涵设计规范[S].
[3]兰宪钢.城市高架桥采用大跨径承台梁跨越地铁车站设计研究[J].铁道建筑,2017(4):30-33.
[4]江甫,秦现德.预应力承台设计探讨[J].城市道桥与防洪,2014(12):62-64.
[2] JTG 3362—2018,公路钢筋混凝土及预应力混凝土桥涵设计规范[S].
[3]兰宪钢.城市高架桥采用大跨径承台梁跨越地铁车站设计研究[J].铁道建筑,2017(4):30-33.
[4]江甫,秦现德.预应力承台设计探讨[J].城市道桥与防洪,2014(12):62-64.