Large Settlement Mean?
Large settlement can be defined as loss of ground in the downward direction due to over-excavation as a result of trenchless pipeline installation methods such as horizontal directional drilling (HDD). This can lead to the formation of voids or sinkholes above the borehole leading to borehole collapse.
There are two types of settlements that can occur during trenchless pipeline installation namely, large settlement and systematic settlement.
Trenchlesspedia Explains Large Settlement
Settlement is generally seen on the ground surface over sub-structures like foundations or over pipelines. It is the vertical movement of soil in the downward direction, especially in soft or loose soil strata. Soil settlements are mainly caused by trenchless construction methods when proper geotechnical investigation to determine the correct method suitable for soil type is not carried out.
When a proper investigation is carried out it helps in the selection of proper methods and tools, special attention if required by the contractor and use of ground improvement methods to control anticipated ground conditions.