On-Site Full-Scale Load Test and Reliability Evaluation of Prefabricated Bridge Substructure for “Pile–Column Integration”

The application of prefabricated bridge structures is of great significance to building industrialization, which can realize the green construction and maintenance process of low energy consumption and low emission as well as the normal operation of transportation in time, and effectively realize the green development requirements. However, the substructure of a conventional prefabricated bridge usually needs to cast a bearing platform between pier and column, and may not give full play to the advantages of prefabricated bridge construction. Given the engineering characteristics that most of the pile foundations in the bridge design of this engineering project are end-bearing piles, in which the pile foundation is not deep and the pile column is not high, the assembly process of “pile–column integration” has been proposed in this study. Aiming at the reconstruction and expansion project of the Qinzhou–Beihai section in the Lanzhou–Haikou expressway, the test site with representative geological conditions was firstly selected. The pile–column structure of the bridge can be completed by prefabricated pile foundation, pier, and cap beam based on the integral assembly installation method. The vertical compressive static load test, horizontal static load test, and reliability test of pile–column connection were introduced in detail to analyze whether the bearing capacity and connection effect of pile–column can meet the requirements. Test results showed that the limit value and corresponding characteristic value of the vertical compressive bearing capacity and horizontal critical load of a single pile could meet the design requirements. The displacement curve of single pile No. 5 at the flange connection position under various loads of the test pile does not have an obvious angle break, and there is no sudden change in the slope, indicating that the flange connection quality is good. Due to many interference factors and some abnormal strain measurement data, the strain data are suggested as auxiliary to the displacement results. The findings of static load testing and connection reliability in this study proved the feasibility of this prefabricated bridge substructure “pile–column integration”, which can provide a reference for the rapid construction of bridges.