WES Theoretical Manual, Part III: Bursting

Bursting is the failure in which the internal pressure of the fill overstresses the interlocks and the sheeting splits. This part explains how to estimate the interlock tension and what to compare it with.

A key point is that the interlock tension and the lateral earth pressure on the cell wall are both greatest at the same elevation, which is close to where the cell bulges the most. That elevation depends on how firmly the foundation holds the embedded sheeting, and the manual locates it with the plane of fixity, the level below which the interlock tension is small. For cells in sand, it gives an equation for the depth to fixity based on the stiffness of the pile section and the horizontal subgrade reaction.

The part also discusses the choice of earth pressure coefficient, noting that proper drainage of the cell matters more than lengthy debate over the exact value. It warns against the older TVA secant formula for crosswall tension, explains why, and notes that measurements show crosswall tension near the arc connection can run about 20 percent above the main-cell tension. For unusual cases, such as removing an interior berm at high water, it points to finite element analysis.