Experimental study of the performance of plastic pipes buried in dune sand

This paper presents a laboratory model to study the performance of plastic pipes installed in dune sand. Model PVC pipes were installed in a rigid steel tank and tested. The model simulated trench construction with the pipe placed in the middle of the tank and dune sand along the boundaries and on the bottom of the tank to simulate the native soil. The bedding underneath the pipe and the backfill around the pipe were constructed using carefully placed and compacted dune sand. For comparison purposes, a well-selected coarse sand was also used as a bedding material. Different factors were considered such as type of bedding, degree of compaction of bedding, soil cover depth, magnitude of applied surface pressure, and load repetition. The experimental results showed that plastic pipes can be installed in well-placed and compacted dune sand bedding and backfill. A minimum soil cover of 2d is required to guard against adverse effects of surface loading on the pipe. The pipe behaved in elastic range during all stages of loading with small amount of unrecoverable deformations upon the removal of all loads. However, significant recovery (or rebound) occurred only after the removal of all applied surface pressure and portion of the soil cover soil up to 1d above the crown.