Improved Design Method for Anchor Blocks Used with HDPE Pipelines

Design of continuous high-density polyethylene (HDPE) pipelines block when connected to a segmented pipeline in water distribution systems commonly requires a concrete anchor. The anchor block resists the pullout of the adjacent joints in the segmented line from Poisson and thermal forces in the HDPE. Current design methods use allowable soil pressures that are extremely conservative, resulting in very large anchor blocks. The system of forces acting on the pipeline is described, and procedures are given to estimate these forces. The paper includes a procedure to estimate three-dimensional effects that account for burial depth and anchor block geometry. A simplified approach that considers anchor block movement is provided, and design methods are given to limit the deformations to acceptable levels of joint/block movements. The method has been used to develop technical specifications for HDPE piping used by municipal water utilities.