Steel beams and channels rolled into a circle and installed horizontally are often used to reinforce soil in trenches. These rings are called walers. Typically, steel sheet piling is driven into the ground behind the walers. This creates a ring template used to protect workers and to allow construction equipment access to an excavated area.
Excavating and pile-driving companies, as well as the Army Corp of Engineers, use walers in their shoring, seawall or cofferdam projects. Since these systems are designed to prevent collapsing, engineers must specify the size of the steel member based on its section modulus. This measure of strength determines how much the waler will yield against the pressure of the earth or water.