Tunnel Works
Shaft Construction
Shaft Construction The Company has constructed a wide range of shafts In all types of ground conditions. Shaft sizes have ranged from 2.0m id. to 15.0m id.by caisson and from 1.5m id. to 30m id. by underpinning.
- The Company constructed the majority of shafts for the Jubilee Line Extension and its shaft jacking system was copied and used by many other contractors.
- More recently at our Lewes contract we constructed 6 No shafts ranging from 4.2m id to 12.5m id. and up to 22m deep through alluvium deposits into water bearing chalk of strengths up to 10kPa.
- Various specialist techniques were used to achieve construction including hydraulic jacking, preaugering the ground and injecting with bentonite/cement grout, excavating the shafts in a flooded condition and tremmie concreting the base.