Bridge jacking is a complex mechanical process that must be combined with strict construction monitoring to ensure structural safety. To explore the structural stress mechanism and safety status of a large-span prestressed concrete continuous girder bridge during the jacking construction process, this study is based on a three-span prestressed concrete continuous box girder bridge, based on hydraulic synchronous lifting technology and high-precision construction monitoring means. It arranges vibrating wire strain gauges and displacement sensors on the pier top section, mid-span section and side span section to obtain real-time monitoring data of the entire jacking process. The research results showed that the stress increment at the bottom plate compressive stress measuring point on the pier top section showed a good linear growth with the jacking amount, while the stress increment at the mid-span bottom plate tensile stress measuring point showed non-linear growth characteristics. In terms of safety assessment, the safety factors of the most unfavorable tensile stress measuring points were all 1.45, which was higher than the safety reserve threshold of 1.2. The safety factors of the compressive stress measuring points reached 2.72~16.80, and the maximum displacement synchronization error of 0.26 mm was far less than the specification limit of 1.5 mm. The results show that during the jacking process, the compressive stress response of the pier top section is the most significant and linearly stable, and the structure is always in an elastic working state. This research provides reliable technical reference and theoretical basis for the safety control of long-span bridge jacking construction.
