大跨度高速铁路劲性骨架混凝土拱桥模型试验研究

Model Test Study on Long-Span Railway Concrete Arch Bridge with Rigid Skeleton

沪昆高铁北盘江特大桥为主跨445 m的劲性骨架钢筋混凝土拱桥,桥面拟铺设无砟轨道,设计时速350 km/h,因此,对桥梁的受力和变形性能提出了很高的要求.为了验证实桥施工过程中的安全性和劲性骨架外包混凝土施工方法的合理性,对全桥进行了1∶7.5的缩尺模型试验研究,对模型的加载方法、控制截面和测点的布置进行了探讨,并将模型的试验结果与计算结果进行对比,全面了解该桥在施工过程中及成桥状态下的受力行为,研究结果表明:劲性骨架施工过程中,钢管最大应力250 MPa,位于1/2截面上弦杆处;主拱圈C60外包混凝土最大压应力为17 MPa,位于1/2截面边箱底板处;主拱圈最大位移为68 mm,出现在1/2截面附近;应力和位移均满足与原桥的应力等效和几何相似关系,模型试验结果均满足原桥施工过程中应力和变形的要求.

The Beipanjiang bridge is a 445 m concrete arch reinforced rigid skeleton bridge on the high-speed railway from Shanghai to Kunming. The bridge deck is designed to comply with design rail speeds of 350 km/h and subsequently requires strictly controlled stresses and deformation for this ballast-less track. To verify the safety of the bridge during construction and in service and to rationalise the use of outsourced concrete construction methods, a 1 ？ 7. 5 scaled model based on the prototype bridge was constructed. The loading method and arrangement of control sections and measuring points are discussed. Comparing the test results and computed results provides a comprehensive understanding of the mechanical behavior of the bridge. The results indicate that the maximum stress of the steel tube is 250 MPa, located at the upper chord of 1/2 cross section and the maximum stress of the C60 outsourced concrete is 17 MPa, located at the side-box bottom of the half cross section, whilst themaximum displacement of the arch ring is 68 mm, also positioned at the half cross section. Considering the stress equivalent and geometric similarity principles, the comparative results indicate that the stress and displacement of the model bridge align with the design parameters of the prototype. Model test results prove that the stress and deformation of the prototype bridge can meet the requirements during construction.