Estimating Maximum Bending Moment in High-Density Polyethylene Pipes under Traffic Loading

High-density polyethylene (HDPE) pipes have been widely adopted for municipal pipeline projects all over the world. HDPE pipe failures, including reduced flow capacity and wall buckling, have been reported extensively, and traffic loading is one of the major causes. Understanding bending moments in HDPE pipes is essential for pipe safety evaluation under traffic loading. However, existing methods cannot accurately estimate the bending moment in HDPE pipes due to neglecting the installation effect and the pipe-soil interaction under traffic loading. The installation of pipes generates an initial bending moment in the pipe, which should be included in the pipe bending moment calculation. The pipe-soil interaction dominates the load sharing between the pipe and the soil and thus influences the bending moment in the pipe under traffic loading. In this study, numerical modeling was used to investigate the bending moment in HDPE pipes caused by traffic loading. A field trial was firstly used to verify the effectiveness of the numerical modeling procedure. Subsequently, the effects of traffic load magnitude, soil cover thickness, pipe diameter, and pipe stiffness on the maximum bending moment were investigated. An empirical method was then proposed to predict the maximum bending moment in the HDPE pipe caused by the traffic loading based on the numerical results. Finally, a case history from the literature was used to validate the proposed method.