高速铁路桥梁支座垫石开裂成因分析及改进措施

随着铁路建设发展,桥梁病害随之增多,其中高速铁路桥梁支座垫石开裂问题突出,严重影响桥梁服役功能及寿命。为研究支座垫石混凝土开裂成因,以某铁路桥梁桥墩加垫石结构为背景,利用ANSYS有限元软件,系统分析了在新老混凝土收缩作用、桥墩与垫石不同龄期差及支座垫石振捣是否密实条件下,新浇筑垫石的应力状况,并提出避免支座垫石开裂的改进措施。结果表明:新老混凝土收缩作用是架梁后支座垫石拉应力产生的主要原因;垫石收缩应力随新老混凝土龄期差增大而增大,最后趋于稳定;支座垫石混凝土振捣不密实会使垫石拉应力增大,导致垫石内部裂缝的产生;垫石浇筑前对桥墩混凝土润湿能有效减小垫石收缩应力,避免垫石开裂。

Cause Analysis and Improvement Measures for Cracking of Supporting Pad Stone of High Speed Rail Bridge Bearing

With the development of railway construction,more bridge diseases have developed.Among these diseases,the cracking problem of supporting pad stone of high speed railway bridge bearing is prominent,which seriously affects the service and the life of the bridge.In order to study the causes of cracking of supporting pad stone concrete,this paper took a railway bridge pier supporting pad stone structure as the background.The ANSYS finite element software was used to systematically analyze the stress state of supporting pad stone under different conditions,such as the shrinkage of new and old concrete,the age difference between pier and supporting pad stone,and the compactness of supporting pad stone vibration.The improvement measures to avoid the cracking of supporting pad stone concrete was proposed based on the research in this paper.The results show that the shrinkage of the new and old concrete is the main reason for the tensile stress of the supporting pad stone after the installation of the girder.The shrinkage stress of the supporting pad stone increases with the increase of the age difference between the new and old concrete,and it tends to be stable at last.The tensile stress of the supporting pad stone increases if the supporting pad stone concrete is not compacted by vibration,which results in the cracking in the supporting pad stone.Wetting the pier concrete before the supporting pad stone casting can effectively reduce the shrinkage stress of the supporting pad stone and avoid the cracking of the supporting pad stone.