刚构桥矩形空心-双薄壁组合桥墩纵向刚度研究

Research on longitudinal stiffness of combined double-thin-walled pier

针对矩形空心-双薄壁组合桥墩纵向刚度的设计方法尚不完善的问题,提出一种基于列车-轨道-桥梁动力相互作用理论的矩形空心-双薄壁组合桥墩纵向刚度确定方法.首先,基于列车-轨道-桥梁动力相互作用理论建立考虑桥轨关系和轮轨关系的列车-轨道-桥梁动力相互作用模型,在此基础上完善钢轨多种附加应力的计算方法;然后,考虑桥墩刚度对扣件上拔力和墩顶纵向位移的影响,以重庆地铁实际工程为例,确定轨道桥矩形空心-双薄壁组合桥墩纵向刚度.研究表明:提出的组合桥墩纵向刚度研究方法可有效用于求解钢轨应力及确定桥墩合理纵向刚度;钢轨底部边缘动弯曲应力和温度应力未随桥墩纵向刚度而变化,而钢轨伸缩应力对桥墩刚度变化最为敏感;桥墩纵向刚度对扣件上拔力以及墩顶纵向位移均有明显影响;对于所研究的矩形空心-双薄壁组合桥墩,其墩底尺寸建议不小于7.4 m,此时刚构桥墩的合成线刚度为61.4 MN/m.

Aiming at the problem that the design method for longitudinal stiffness of combined rectangular-hollow pier and doublethin-walled pier(RHP-DTHP) is not perfect enough,a method to determine the longitudinal stiffness of RHP-DTHP was proposed based on the train-track-bridge dynamic interaction theory.First,a train-track-bridge dynamic model was established based on the train-track-bridge dynamic interaction theory considering wheel-rail interaction and track-bridge interaction,and on this basis the method to perfect rail additional stress was completed.By adopting the established models,considering the influence of pier stiffness on fastener force and pier-top longitudinal displacement,the reasonable longitudinal stiffness of RHP-DTHP is determined based on the practical engineering problems in Chongqing metro lines.Research results show that the proposed method is effective to calculate rail stress and determine reasonable pier longitudinal stiffness.Dynamic bending stress at edge of rail-bottom and thermal stress are not sensitive to pier stiffness,while stretch stress is most sensitive to pier stiffness.For the RHP-DTHP studied in this work,the width of pier-bottom is suggested to be no larger than 7.4 m,while the combined line stiffness of the rigid frame bridge is 61.4 MN/cm.