Concrete piles, bored and cast-in place, enable the economical installation of larger diameter piles and permit construction through particularly stiff or hard soil. ‘Dry’ and ‘Wet’ boring methods are used, depending on ground conditions.
‘Dry’ method employs the use of a temporary steel casing to protect against soil collapse and water ingress into the pile bore in unstable strata overlying stable strata. Once the design depth is reached, a reinforcing cage is inserted, and is then followed with concrete poured into the bore up to the required level.
‘Wet’ method is used when the pile bore cannot be sealed against excessive water ingress. A digging bucket instead of auger is used to drill to the design depth. Reinforcement cage is then placed, and concrete is cast by means of a tremmie pipe to form the pile.
The pile walls are used to resist vertical loads, in addition to moments and horizontal forces commonly found in basement construction. Contiguous pile walls are constructed with bored piles having small gaps in between them. The size of this gap is determined by the nature of the soil minimize “soil flow” into the excavation.
Secant walls are formed by constructing intersecting reinforced concrete bored piles between primary piles constructed earlier. Secondary piles are installed only after the primary piles have gained enough strength to form a “water-right” wall protection an excavation.
Driven piles are prefabricated piles into the ground using a hydraulic hammer or a diesel pile driving rig. Driven piles are typically of concrete or steel. Concrete piles are available in square, octagonal, and round cross-section. Some are reinforced by prestressing. Steel piles are either pipe piles or ‘H’ beam section.
Soldier piles, or king posts, are constructed of wide flange steel H sections with spacing 2-4m apart, driven in before excavation. In basement wall construction, timber lagging is installed behind the steel H sections to shore up the cut soil face.
Soldier pile walls are the least expensive systems compared to other temporary retaining walls. They are also fast and easy to construct.
Grouted Micropiles ranging from 150mm to 500mm diameters, Driven Micropiles, Ground Anchors, Soil Nails/Shotcrete, Rock Bolts, Slope Stabilisation, Soil Improvement and related specialist Geotechnical works.