TPMD operate a modern and comprehensive fleet of pipejacking equipment capable of installing pipelines ranging from 1200mm to 2400mm in diameter.
The basic concept of pipe-jacking is well established, and is capable of installing concrete, steel or in certain circumstances GRP pipes by systematic face excavation.
Powerful hydraulic jacks within the drive shaft are used to push the jacking pipe through the ground. A steel tunnelling shield at the head of the pipeline is used to provide support for the excavation process and to provide directional control for the pipejack. Excavation techniques cover a wide range, from simple hand mining to backhoe and roadheader machines through to sophisticated full face earth pressure balance shields.
Open face Tunnel Boring Machines (TBMs) such as backhoe or roadheader shields are suited to dry stable soils and soft rock. Full face Earth Pressure Balance TBM’s may be used when ground conditions are more difficult and where the pipeline is to be constructed below the ground water table.An accurate alignment is maintained by following a laser set to line and grade. The shield is steered to the laser line with adjustments made to the on-board steering jacks.
Drive lengths vary depending upon excavation technique, ground conditions and pipe diameter. The use of a lubricant injected through ports in the jacking pipes and the provision of intermediate jacking stations enable longer drives to be carried out.