What Does Dog Plate Mean?
The dog plate is the heavily fortified area at the rear of the access pit in a pipe ramming operation. The dog plate is directly opposite the end of the pit where the pipe is jacked into and through. Since every action, such as ramming a pipe through the ground, creates a force in one direction, there's an equal and opposite force in the opposite direction: the RAM is forced backward in the access pit.
The dog plate spreads those forces placed on the ram across the entire rear wall of the access pit, an area larger than the area of the edge of the pipe being rammed.
Trenchlesspedia Explains Dog Plate
The dog plate demonstrates how pipe ramming takes advantage of Newton’s laws of motion. Newton’s Third Law states that All forces in the universe occur in equal but oppositely directed pairs. There are no isolated forces; for every external force that acts on an object, there is a force of equal magnitude but opposite direction which acts back on the object which exerted that external force. In other words, for every action, there is an equal and opposite reaction. The force created by the action of the ram in pipe ramming must be countered by something.
The “something” and pipe ramming is the back of the access pit. Since the dog plate distributes (and reduces) the jack’s force over a greater area at the back of the pit than at the end of the pipe, the jack pushes the pipe forward; the pipe doesn’t push the Jack backward – a simple use of Newton’s First Law (a body at rest tends to remain at rest unless and until it’s acted on by greater force).