What Does Jacking Loads Mean?
Jacking load is the term used to describe the amount of force needed to push the micro- tunneling boring machine (MTBM) forward in a pipe jacking operation. The jacking load is calculated as the sum of the force required to overcome the resistance of the tunnel face and the frictional force of resistance to movement of the pipe through the bore. Understanding the jacking load for a specific ground condition enables the correct sizing of pipe jacking equipment.
Trenchlesspedia Explains Jacking Loads
Microtunneling boring machines (MTBMs) have rotating cutting heads to cut through the ground as the jacks push the MTBM forward. The effectiveness of the machine depends on the selection of the cutting head and the force supplied by the jacking equipment. Harder ground and larger diameter bores require greater force to push the cutting head forward. As the bore progresses, a longer and longer length of pipe casing lies in the bore behind the cutting head. The jacking equipment needs to overcome the natural friction of the soil pushing against the casing in addition to the force required to advance the cutting head.