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

Typical applications

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

Installation 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.

Key benefits

  • 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