Effect of voids on the bending response of buried flexible utility pipes

Buried pipe infrastructure is of critical importance for the provision of fresh water supply and disposal of waste water. Pipe performance is sensitive to initial ground burial conditions and subsequent changes during serviceable life. Voids are frequently reported as a possible factor that accelerates deterioration of the pipe condition leading to ultimate premature failure in flexure or cracking. This study considers the effect of voids on a 0.3 m prototype flexible pipe for fully supported and unsupported conditions buried in sand using centrifuge model tests. Pipe stiffness and bending response for spherical void geometries 2 to 5 times that of the pipe diameter are evaluated when subjected to vertical surface loading. Digital image correlation is used to capture soil-pipe interaction mechanics. Increased pipe deformation and bending moment were observed with increased void size confirming that void formation may contribute in the overall failure of pipe infrastructure.