Responses of Small-Diameter Steel Pipes Buried in Sand under Lateral Ground Movement

Pipelines subjected to ground movements are typically assessed using beam-on-spring analysis. Current design guidelines recommend spring parameters developed based on studies on rigid pipe segments. However, the applicability of the parameters for simulating the responses of pipes with different flexural rigidity was not extensively evaluated. The current study focuses on developing a database for steel pipes with different flexural rigidity to assess the current design guide recommendations. Full-scale laboratory tests were conducted on 1.9-m-long steel pipes of three different diameters (26.7, 60.3, 114.3 mm) buried in dense sand at an embedment depth of 0.6 m. The force–displacement responses, pipe strains, midspan deflections, and soil surface images were obtained during the tests. The findings suggest that the lateral load–displacement response can depend on the pipe diameter, H / D ratio, and relative flexural rigidity of the pipe, whereas some previous studies indicated that the load–displacement response depends solely on the H / D ratio. The maximum longitudinal strains occurred at the pipe center for pipes with higher flexural stiffness, whereas the maximum strains occurred near the ends for flexible pipes. For the flexible pipes, soil resistance during tests is first mobilized near the pipe ends and then gradually extends toward the midspan, indicating different load-transfer mechanisms. Therefore, researchers should be cautious when normalizing peak lateral force and dimensionless yield displacement to estimate spring parameters from flexible pipe tests.