Shoring is a general term used in construction to explain the activity of supporting a structure in order to prevent cave in so that construction can proceed. The phrase can also refer to the components used in the operation. Trench hydraulic shoring is the process of bracing the walls of a trench to prevent collapse. The phrase can also be used as a noun to refer to the materials used in the process. During excavation, shoring systems provide safety for workers in a trench and speed excavation. In this case, shoring should not be confused with shielding. The purpose of shoring is designed to prevent cave-in where shielding is only intended to protect workers when collapses occur. Concrete structure shoring, in this case also referred to as falsework, provides nonpermanent support until the concrete becomes solid and achieves the desired strength to support loads.
Hydraulic Shoring Methods
Several methods can be used to shore up a trench. Hydraulic shoring is the use of hydraulic pistons that can be driven outward until they push up against the ditch walls. It is great for working around existing utilities, supporting trench walls near construction, trammels, or walkways, and for pipe installations where a larger backhoe cannot be used. Most shores can be installed and removed from the surface, safely and easily. They are typically combined with steel plate or a special heavy plywood called finform. Semi-pliable laminated finform panels bend slightly to support uneven trench walls in cave-in situations. FinForm is used to thwart sloughing of ditch walls and is not judged to be a structural member.
Another method is called beam and plate, in which steel I-beams are driven into the soil and steel plates are slid in the middle of them. An almost identical method that uses wood boards is called soldier boarding. Hydraulics tend to be faster and easier; the other methods tend to be used for longer term jobs or larger excavations.
Shoring is not Shielding
Shoring should not be considered the same as shielding by means of trench shields. Shoring is designed to prevent collapse, shielding is only intended to protect workers should collapse occur. Most experts concur that shoring is the safer approach of the two.
Shores are used to actually apply pressure to trench walls to prevent cave-ins. Shores are an excellent lightweight resource for working around existing utilities, supporting trench walls near structures, curbs, or sidewalks, and for drain installations where a larger backhoe cannot be used. Most shores can be safely and easily installed and removed from the surface, thus avoiding the risk of working in an unshored ditch.