This type of pile is used to provide a piering system that is ideal for use where various load cases are applied to the pile, from uplift and tension to lateral load, or where moment or large pile loads are required. Bored piers are an effective solution for supporting significant/heavy vertical and horizontal structural loads, with an allowable bearing capacity of up to 13,800 kN.
Bored piers are generally used as a foundation for:
Bored piling is ideal for use in built-up urban areas or industrial settings, because of its minimal vibration and its minimal deformation of the adjacent ground or soil mass.
This method of piering is often used to provide a foundation solution on sites where ground conditions are generally fair to good, with a ground mass of rock, firm strata, or cohesive soil. When drilled in to rock, bored piles help to minimise foundation settlement.
However, bored piers are not ideal for ground conditions where soil has a higher water content, due to a shallow water table, nor are they suited to sites where removal of excavated materials is problematic – for example, where the spoils are contaminated by substances such as acid sulphates or asbestos.
Bored piles are constructed using a modern drill rig to bore a hole of the required diameter. The process involves repeatedly drilling, then withdrawing the drill to remove ground material from the pile, until the required depth is reached.
Excavated ground materials are removed from the drilled shaft using purpose-designed drilling tools, including rock and soil augers, core barrels and clean-out buckets. Once drilling has been completed, the drilled shaft is cleaned and a steel reinforcement cage is placed in situ, then concrete is poured into the shaft. A plunger tube is used for concreting in the presence of water, to avoid segregation of the concrete – this is known as the tremie pipe technique.
The sides of the shaft are supported throughout the construction process, with the method of support being selected in line with the nature of the ground being drilled into (for example, soft or hard rock, soft or non-cohesive soils, or stiff clay), the identified groundwater level, and any other environmental constraints. The use of steel reinforcements, such as a steel casing or liner, to shore the walls (sides) of the pile and prevent ground materials from collapsing back into the hole, may be temporary or permanent.
Bored piles offer the largest possible pile diameter –up to 4 metres. Our drilling equipment is capable of drilling to a depth of up to 90 metres.
For more information, contact the piling experts at Solmer Civil on 0418 497 921.