Field Test for Buried Large Steel Pipes with Thin Wall

Field buried pipe tests were conducted using steel pipes with 3500mm-diameter and 26mm-thickness as a part of Irrigation Pipeline Project. In current design for irrigation pipeline in Japan, there are no design criteria for pipeline with diameter larger than 3000 mm. In the field tests, two cases of backfilling methods were employed. In Case 1, soil-cement was used as backfill material to a height of half the diameter measured from the bottom of the pipe. In Case 2, soil-cement was used as backfill to a height of quarter diameter measured from the bottom of the pipe. The mixed rock, which was recycled crushed concrete and crushed gravel, was backfilled above soil-cement to the top of the pipe. The pipe was buried under a depth of approximately 3.0 m in both cases. Displacement transducers were installed in the pipes and strain gauges were attached to the inner of the pipe. Earth pressure transducers and pore water pressure transducers were installed in the backfill materials around the pipes. The deformations in each of the backfilling stage were measured. It is found that the behavior of the buried pipe was strongly influenced by backfilling methods and external force.