Abstract:The design standard of a newly-built road is a two-way six-lane urban trunk road. The reserved holes of existing bridges should be used in alignment layout. The bridge piers should be arranged according to the condition of crossing two-way four lanes. The reserved width cannot meet the design requirements of the new road. In order to realize the continuous function of the new trunk road and avoid the formation of traffic bottleneck, the reconstruction of the existing bridge piers is analyzed. The reconstruction target is one of the middle piers of the three-span prestressed concrete continuous beam bridge, which is located in the motor vehicle road range of the newly-built road. On the premise of not affecting the bearing capacity of the bridge, not changing the stress system of the bridge, ensuring the safety of the bridge operation and reducing the influence on the current traffic, two design schemes of active and passive underpinning reconstruction are put forward, and the specific implementation steps are formed. According to the respective design contents, the underpinning methods, settlement controls, main beam stresses, technological difficulties, bearing effects, landscape effects, traffic impacts and the other specific characteristics are comprehensively compared. The final scheme is determined combined with the characteristics of the original bridge structure system. Finally, a certain conclusion is formed, and the characteristics and applicable conditions of active underpinning and passive underpinning are summarized so as to form a certain reference for the design of the subsequent similar projects.
