What Does Entrance Pit Mean?
An entrance pit is an excavated pit, an opening located at the entrance of the cutterhead or casing which is the starting point for a pipe jacking or microtunneling operation. The entrance pit is used to install the drilling equipment and associated ancillaries, including the thrust wall, so that the tunnel can be bored from that point.
Entrance pits are minor excavations compared to digging open trenches along the full length of pipe installation.
Trenchlesspedia Explains Entrance Pit
A pipe jacking or microtunneling trenchless installation has a beginning point, desired route and ending point. Pits must be excavated at the beginning and ending points in order to make room for the equipment to be positioned for the boring process. In order to begin the bore, the drilling equipment must be installed in the entrance pit and positioned to enable the tunnel direction towards the receiving pit.
As each casing or pipe length is installed into the bore, the next one is lowered into the entrance pit to repeat the process. Once the bore is complete, the equipment is removed from the entrance pit.