Definition - What does Settlement Control mean?
Settlement is the collapse of soil below the ground surface leading to voids or troughs on the surface. Settlement control is the use of all means possible through design and execution of a trenchless project in order to prevent this collapse of soil. Settlement can lead to project delays and increased costs to rectify the problem as well as unintended environmental damage.
Trenchlesspedia explains Settlement Control
There are two primary categories of settlement. Large settlements are caused by over excavation and can be controlled through proper geotechnical investigations, setting an appropriate depth of the tunnel and adherence to the best practices by the construction contractor.
Systemic settlement is the collapse of soil into the annular space around the new pipe installation. It can be caused by inadequate drilling fluid pressure and quality. It may be necessary to grout the space around the pipe in cases where soil stability is a concern.