Study On Safety Monitoring Technology Of Prestressed Concrete Bridge Pier Based On BOTDA

Distributed optical fiber sensing technology has been applied in many important structure’s monitoring because its huge advantage, but it’s first time in the pre-stressed concrete bridge pier beam hydration heat and pre-stress safety monitoring. How to arrange the optical fiber in the structure? How to improve the fiber’s survival rate and how to distributed monitor the pre-stressed steel strand in the body? There are many problems are not resolved. On this basis, this article has carried on the following research and explore.1 Comparative analyzed the advantages and disadvantages of the traditional monitoring methods, analyzed the theory feasibility and advantages of the distributed optical fiber technology been applied to the pre-stressed concrete bridge pier beam hydration heat and pre-stress monitoring.2 Theoretically analyzed the change mechanism of mass concrete and the factors affecting the stress of pre-stressed steel strand; Provided a theoretical support to establish the mass concrete hydration heat three dimensional temperature field and the pre-stressed steel strand simulation.3 Through field experiment, established a complete set of monitoring system to monitor the pre-stressed concrete hydration heat and pre-stress based on BOTDA. Established the pre-stressed concrete beams’ visual three-dimensional temperature field.4 Combining with the experience of the fiber laying, effectively solved the problem of how to lead the fiber in body out of the structure.5 Simulated the bridge pier beam pre-stressed loading process; Analyzed the influence range and size of the pre-stressed steel strand under different tension stress conditions.Based on the above research, obtain the following results:1 Achieved hydration heat monitoring of the pre-stressed concrete beams based on BO TDA for the first time, revealed the three-dimensional temperature field change rule of the pre-stressed concrete beam.2 Achieved the distributed strain monitoring of pre-stressed steel strand for the first time, revealed the steel strand’s stress change process under multiple loads in the construction process.3 Lay the sensing optical on the surface of pre-stressed steel strand, distributed monitoring the stress attenuation process of the pre-stressed steel strand; Provide a new monitoring method to monitor pre-stressed structure, especially for pre-stressed steel strand in body structure; 4 There is an obvious stress attenuation process after the completion of the pre-stressed steel strand tensioning construction, the time needed for the process can be very long, but within one month after the completion of tensioning construction, attenuation can reach more than 75% of the total attenuation.