The Influence of Non-Uniform Bedding on the Mechanical Behavior of Buried Flexible Pipe

The soil around the buried pipe may become loose locally because of large earthquake and torrential rain, and the bedding may become non-uniform. However, the effect of non-uniform bedding on buried pipe remains to be clarified. In this study, experiments were conducted in order to clarify the behavior of buried pipe on the non-uniform bedding. The experimental pit has 64 holes (100 mm×100 mm) with valves at the bottom to create the non-uniform bedding. Polyvinyl chloride pipe, having a diameter of 600 mm and 3 measuring sections (Section-A, B, and C), was used. The distance between sections was 200 mm. The test showed that, when the sand was removed from the pipe bottom level around Section-A and Section-C, the pipe moved asymmetrically. As a result, when the ground becomes loose locally, large tensile strain acted on a Section-A (C) of the pipe closest to loosened ground, but maximum shear strain decreased. On the other hand, at the mid-section (Section-B) between the sections, which was close to loosened ground, circumferential tensile strain hardly occurred, but principal tensile strain acted almost in a pipe axial direction. Maximum shear strain at the mid-section increased to have a risk of yield failure.