ABSTRACT
The mechanics of gravity flow sewers and culverts has been well explained in the twentieth century, with contributions on rigid (e.g. Marston and Anderson, 1913) and flexible (e.g. Spangler, 1956) structures, and rational analyses developed since the 1960’s that explain how pipe stiffness relative to the surrounding ground influences the stability limit states (e.g. Hoeg, 1968). While there might seem little need for further research, the processes by which the stability of pipes change over time are only now being
studied (e.g. Tan and Moore, 2007; E1 Taher and Moore, 2008), considering the roles of pipe deterioration (fractures in rigid structures, Figure 1a, and corrosion of flexible metal structures, Figure 1b), as well as soil erosion. Figure 2a shows an erosion void visible beside a metal culvert, developing after wall perforation. Similar voids develop besides rigid pipe structures (Spasojevic et al., 2006).
