预应力混凝土箱梁桥桥墩位移事故机理分析

针对桥墩位移事故致因的复杂性及分析过程的不确定性，以某预应力混凝土箱梁桥桥墩因上游侧的新填土造成堆载作用导致土体侧向位移影响桩基受力的位移事故项目为研究对象，通过现场检测、监测及理论分析了与数值模拟相结合的综合分析方法，模拟并分析桥墩位移事故的致因，梳理病害产生的内在机理。结合现场实际情况，以分级处理为处置原则，采用桩基顶推、墩顶牵引、设抗滑桩、平衡堆载等组合措施进行纠偏处理并对病害进行整治，使桥墩偏位回归至允许范围内，缺陷得到修复。在纠偏处理过程中对桥墩、抗滑桩和锚杆等进行动态监控，结果表明，各项位移指标符合要求，事故分析过程准确，所采取的方案有效合理，处置效果良好。该研究为同类事故事后调查及病害成因分析、纠偏处置提供了参考。

Mechanism analysis of bridge pier displacement accident ofa prestressed concrete box girder bridge

For the complexity and uncertainty of analysis process of pier displacement accident, we simulate and analyze the cause of pier displacement accident and its internal mechanism with the impact of surcharges action of recent fill caused lateral displacement of soil pile of a prestressed concrete box girder bridge pier on the force of pile foundation as a subject and the combination of on site inspection, comprehensive monitoring and theoretical analysis and numerical simulation. We employ pile top push, pier top traction, anti slide pile, balance load to conduct rectification and accident management based on hierarchical processing principle and actual situation. Pier deviation therefore returns to the allowable range, and the accident is avoided. We also dynamically monitor the pier, anti slide pile and anchor rod in the rectification process. Results show that all displacement indicators satisfy the requirements, so the accident analysis is accurate, and the scheme is reasonable and effective and has better disposition effect. The method provides reference for postsurvey of similar accidents, analysis of accident cause and rectification process.