Minipiles are a deep foundation element constructed using high-strength, small-diameter steel casing and/or threaded bars.

Common uses

Provide structural support to most structures
Underpin foundations
Enhance mass stability
Transfer loads

Process

The casing, with a diameter generally in the range of 200-600mm is advanced to the design depth using a drilling technique.

Reinforcing steel, typically an all-thread bar, is inserted into the minipile casing and high-strength cement grout pumped in. The casing may extend to the full depth or end above the bond zone with the reinforcing bar extending to the full depth.

Capacities vary depending on the minipile diameter and subsurface profile but compressive capacities of more than 1000kN have been achieved.

Advantages

Can be installed in restricted access and low headroom sites with minimal disruption to operations
Resists compressive, uplift/tension, and lateral loads
Piles can bond with existing structures such as bridge foundations to support loading increases
Alleviates quality assurance concerns associated with cast-in-place piling in weak soils
Can be combined with other techniques to meet unique or complex project requirements cost-effectively and efficiently
Electric rigs can be used to reduce carbon emissions

Quality assurance

Keller has vast minipiling experience in all ground conditions with the ability to design in-house based on subsurface conditions, structural requirements and environmental limitations.