Here at leitir tunnelling we can sink segment shafts from 2m to 20m and sheet piles shafts from 1.8m to 10m to your required depth ,sheet pile shafts are installed by excavating the ground to 1m and then building 2 shaft frames the frames are then sheeted around with piles ,the ground is then excavated within the shaft as the ground is being excavated the sheets are pushed down and the bottom frame is lowered to support the ground this continues until formation level is reached ,
With segment shafts we excavate 1.2m bigger than than the required shaft size down to 1.2m deep then the shaft cutting edge is built with the first shaft ring being built on top it is then wrapped in 25mm polyester and concrete is poured around the outside of the shaft up to ground level forming the shaft collar ,after the concrete sets the shaft jacking rams are put in place around the shaft and the ground is then excavated within the shaft using our clamshell grab the shaft is then jacked down and another ring is built on top of the first ring this is repeated until the required level is reached, then a concrete base is poured , grout is then pumped behind the shaft rings forming a water tight shaft , these shafts can be used for pipe jacking /timber heading ,pumping stations,tunnel vent shaft ,or can be mass filled with concrete to form piles for structures, etc