Experimental Study of the Effects Produced by a Backfilling Process on Full-Scale Buried Corrugated HDPE Pipes in Fine-Grained Soils

High-density polyethylene (HDPE) pipes are widely used throughout the world due to their significant advantages. Most of the previous studies have focused on the behavior of the pipe-soil system under live loading and the development of theories and design methods. However, studies on the effect of construction on the response of HDPE pipes buried in fine-grained soils have not been well understood. In this study, a full-scale field test was conducted to investigate the earth pressure and deflection of three profile-wall corrugated HDPE pipes during installation in fine-grained soils. Pipes with diameters of 300 and 600 mm were buried in trenches with a width of 2.0 m. The test results demonstrate that the pipes deformed into a vertical ellipse before the backfilling reached the top of the pipe level and then gradually rerounded afterwards. The measured vertical earth pressure above the top of the pipe was lower than the overburden stress and pressure calculated using the Marston load theory, which is attributable to the positive soil arching developed in the backfill and the effect of compaction. When the backfilling level was above the top of the pipe, the lateral earth pressure at the pipe springline was approximately two times the corresponding geostatic pressure, which was attributed to the soil arching developed in the soil cover. Linear functions were proposed to correlate the measured pipe deflections both in the vertical and horizontal directions with the soil cover thickness. The proposed vertical deflection-soil cover thickness relationship was validated using the data reported in a previous study. An empirical equation was also developed to quantify the unique relationship between the ratio of vertical deflection to horizontal deflection and the soil cover thickness. (C) 2015 American Society of Civil Engineers.