High-pressure soilcrete columns — Soilmec SM-3 jet grout rig for underpinning, liquefaction mitigation, and groundwater control.
Jet grouting is a specialist ground improvement technique that uses high-energy fluid jets to erode and mix the in-situ soil with cementitious grout, creating columns or panels of soil-cement with significantly improved strength and reduced permeability. Depending on the energy regime and fluid system used (single, double or triple fluid) jet grouting can be applied in a wide range of soil types and can create column diameters from 600mm to over 2000mm.
Jet grouting is particularly valued in New Zealand for its ability to improve the ground beneath and adjacent to existing structures without causing vibration or requiring excavation. It can be used to create load-bearing columns beneath buildings undergoing foundation improvement, to form cut-off walls for groundwater control, to underpin existing foundations and to provide temporary or permanent excavation support in soft ground.
APPLICATIONS
GSI NZ CAPABILITY
THE GSI DIFFERENCE
Step 1
Ground investigation data defines soil type, groundwater conditions, and treatment depth. Column diameter and layout are designed to the specific application: underpinning, cut-off wall, liquefaction mitigation, or excavation support.
Step 2
The SM-3 drill string is advanced to the treatment depth. Ultra-high-pressure grout jets erode and mix the native soil as the string is withdrawn at a controlled rate, forming a soilcrete column of the designed diameter and depth.
Step 3
Real-time data logging monitors grout pressure, flow rate, and withdrawal speed for every column. Post-installation coring and UCS testing confirms column strength. Permeability testing is carried out where cut-off performance is the primary criterion.
CASE STUDY
GSI NZ was engaged by CPB Contractors to deliver jet grouting for the Metrosports Christchurch aquatic facility, a major post-earthquake rebuild project on liquefiable ground. Aurecon provided the geotechnical design.
107 soilcrete columns were installed to 15 m depth to mitigate liquefaction risk beneath the facility footprint. The compact SM-3 rig allowed installation within the building footprint and around existing structural constraints — a project only viable because the SM-3's compact geometry could navigate the working environment.
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107 soilcrete columns to 15 m for liquefaction mitigation, Christchurch post-earthquake rebuild.
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126 soil-cement columns to stabilise an active landslide mass, Central Hawke's Bay.
View Project →GROUND ENGINEERING
CFA piling and GCS wall on a constrained coastal site in Napier.
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Jet grouting reaches where other methods can't — under live structures, in confined spaces, in variable ground. Our engineers have delivered it across New Zealand and Australasia.
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