This investigation is a study of some of the factors which affect the ability of a plastic pipe to support earth loads. Some of the factors that were considered are the strength of the pipe and the soil conditions.Two series of laboratory tests, using two soil densities, were conducted on two types of plastic pipes that had six wall thicknesses. Deflection gauges were used to measure changes in the inside diameter due to an external load that was applied on the buried specimens.The results indicated that loose soil fill will produce about 70% more vertical deflection in a pipe than dense soil fill. Also, it was observed that vertical deflections can best be assessed by considering the resistence of the pipe to membrane forces rather than bending moments as stipulated in the A.S.T.M. Specifications.
