Experimental and Numerical Study of High Fill Culvert in Mountainous Regions

The mechanical behavior of assembled culverts under high rocky backfill presents significant challenges due to the complex interaction between the rigid structure and coarse-grained fill. This study investigates the full-process mechanical performance of an assembled culvert through comprehensive in situ monitoring and three-dimensional finite element numerical analysis. Key parameters, including earth pressure distribution, structural deformation, and joint strain, were continuously monitored throughout the backfilling process. A high-fidelity numerical model considering the soil-structure interaction was established and strictly validated against field data. The results indicate that the earth pressure growth rate gradually decreases with fill height, confirming the development of a soil arching effect within the rocky backfill. The numerical predictions show strong consistency with experimental measurements, verifying the model’s accuracy. Crucially, the culvert exhibited minimal deformation, with cumulative settlement less than 25 mm, fully meeting safety requirements. Furthermore, a distinct alternating tension-compression strain pattern was observed at the joints during early backfilling, highlighting the critical necessity of symmetrical layered compaction. These findings validate the safety of the proposed construction methodology and provide a theoretical basis for optimizing the design and quality control of high-fill infrastructure in mountainous terrain.