Unlike trench boxes that can withstand collapsing soil, shoring cannot tolerate it. Shoring relies upon good cohesive soils…soils that remain vertical long enough to install the shoring. Once leveled and brought up to the required pressure, the shoring acts like a shotgun blast to the soil. It starts out focused; but as the pressures begin to build, these compressive forces fan out in all directions compressing the soil even further. In doing so, shoring takes away the earth’s ability to subside. These compressive forces are often times referred to as “The Arch Effect”.
In order for the shoring to truly do its job, the worker must surround himself with this arch effect. This is accomplished by installing the shoring in columns with the worker remaining within these shored columns. The number of shored columns and the number of shores per column is dictated by the manufacturer.