Definition - What does Cased Bore mean?
A cased bore is one that has been drilled with a sleeve in place to prevent soil collapse. Cased boring is a trenchless method of installing pipelines using horizontal augers or pipe jacking. A steel casing also known as sleeve is installed as the borehole progresses requiring minimum overcut. This is an excellent method for boring in sensitive areas where displacement of soil or upward thrust needs to be avoided. This method can also be utilized in varying soil conditions, under airports, roads and railways with little disturbance to surface traffic.
Trenchlesspedia explains Cased Bore
An auger boring machine is set on a track system to drill horizontal bores. The rotating cutting head attached to the auger bores the hole while simultaneously jacking a steel casing behind it. The auger boring machine transfers torque to the cutting head through augers that remain within the casing. Hydraulic jacks are used to push the machine forward.
The helical winding augers also work to transfer the spoil from the cuttings back outside. The simultaneous installation of the sleeve keeps the bore stable and aligned. Where there is sufficient space, the cradle system is used instead of a track system that allows for assembling the entire length of casing along with the cutting head in the launching pit.