Ventilation & Access Shaft Piling

Ventilation & Access Shaft Piling

Tunnel and mining projects requiring vertical access shafts for the supply of construction materials,  ventilation and the introduction or removal of plant, make use of Vibropile's capacity to excavate shafts from the top down, to very demanding vertical tolerances.

BLIND SINK

Suitable for stable ground conditions and to diameters of up to 7 metres, this method of excavation avoids the usual delays associated with raise-boring methods, where the shaft spoil must be removed along the tunnel and raise-boring therefore cannot be started prior to tunnelling reaching the proposed shaft location. Large crane-attached drilling rigs must be used due to the size of the drill tooling required for blink sink shafts. Generally a pilot hole is installed over the full depth of the shaft and then progressively reamed out to the required diameter. Vibropile have installed shafts up to 7m in diameter and to depths approaching 100m.

SECANT SHAFTS

For larger diameter shafts through unstable soils, the use of interlocking hard / soft CFA piles is a highly cost effective method of shaft sinking.
Constructing a shaft typically involves four main stages:

  1. Piles are drilled to required depth to form a continuous wall for the shaft.
  2. A ring of reinforced concrete is constructed around the top of the shaft to support the shaft wall.
  3. Once the outer frame is in place, the main shaft is excavated  out with the material lifted to the surface. Stockpiled material is then loaded by excavator onto trucks and disposed of.
  4. Shaft excavation is stopped at specific depths to construct reinforced concrete or steel support rings. Excavation is then completed to the required depth and a steel reinforced concrete slab is constructed at the base of the shaft.