A STUDY ON BEHAVIOR OF VU PIPE WITH OVERBURDEN PRESSURE UNDER APPLICATION OF INTERNAL LOADING METHOD

Abstract

 Internal loading method (ILM) has been proposed as a evaluation method for the strength of buried pipes. The purpose of this method is to evaluate the deterioration of a pipe or backfilling soil from the relationship between load and deformation of a buried flexible pipe by loading from the inner surface. On the other hand, flexible pipes account for about 90% in the extension of agricultural pipelines, and application of this method to flexible pipes is particularly required. In this study, the effect of overburden pressure on the behavior of the pipe was investigated by installing a VU pipe into the model ground with different earth pressure under ILM. As a result, with lager earth pressure, the inclination of load-deformation curves became larger, and the curve lines turned to linear. In addition, the inclination of buried VU pipe under repeated loadings, became larger at the second and subsequent loadings than the first loading. It was thought that the soil stiffness had increased by the stress history of the first loading.