基于钢轨应变监测的多跨铁路简支梁桥桥墩差异沉降识别

摘要

旨在建立基于钢轨应变监测的多跨铁路简支梁桥桥墩差异沉降识别方法。首先，针对对称转角沉降模式的分析表明钢轨与梁体竖向变形具有一致性，为建立沉降致钢轨应变与桥墩差异沉降关系方程奠定了基础。其次，采用空间梁单元、实体单元、弹簧单元，结合主从自由度耦合技术，建立了某4跨铁路简支梁桥的钢轨-梁体-桥墩有限元模型。基于该模型的分析表明，轨底可测应变与桥墩差异沉降间存在显著正比例线性关系且应变绝对变化量可测。然后，通过理论推导，得到了沉降致钢轨应变与简支梁桥桥墩差异沉降量之间的解析表达式。解析式物理意义明确，表达形式简单。最后，对解析解与数值解进行了对比分析，两者变化趋势相同，解析解因未考虑外围钢轨约束、下部梁体弯曲变形等，所得结果略大于数值解。%The research was conducted in order to establish a method to identify the differential settlement of the piers for the multi-span railway simply supported girder beam (RSSGB)based on track strain monitoring. The vertical deformation consistency between the track and beam,verified in an analysis aiming at the symmet-ric corner settlement model,laid a foundation for establishing the relation equation concerning settlement in-duced track strain and differential settlement of the piers.In addition,the track-beam-pier finite element model (FEM)of a four-span RSSGB was established by using the space beam element,solid element and spring ele-ment,combining the coupling technology of master-slave degrees of freedom.The FEM analysis results pres-ented a positive proportional linear relationship between the measurable strain of the bottom rail and the differ-ential settlement of the piers,and the absolute strain variations of the bottom rail were measurable.Simple with a clear physical meaning,the analytical expression between the settlement induced track strain and pier differential settlement was also obtained through theoretical analysis.The comparison between analytical and numerical results showed the same variation tendency between the two methods.The analytical results were slightly larger than the numerical results due to the ignorance of the restraint of the outer track and the bending deformation of the beam.