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New Zealand
Sub-industry
Residential Apartments
Problems
Earthquake Remediation
Location
Christchurch, NZ
Year
2013
Solutions
Slab Lifting
Technology
JOG Computer-Controlled Grouting, JOG Grouting
Apartment Building Subsidence Remediated
Summary
A shallow, weak soil stratum under a heavy-weight concrete six-storey apartment block in Christchurch had caused the building to suffer differential settlement of up to 70mm after the recent earthquakes.
It was rectified using Jet Grouting to strengthen the foundation ground and by using JOG Computer-Controlled Grouting to raise the building back precisely to its design levels.
Objectives
Firstly to strengthen the entire foundation ground and secondly, to correct the settlement and precisely re-level the whole building.
Solution
1. Jet Grouting method.
Installation of 22 Jet-Crete columns under the critical load points of the building to support and transfer loads down to the gravels. (These columns are sometimes called “soil- crete”, being a mix of cementitious grout and in-situ soil).
2. JOG Computer-Controlled Grouting levelling method.
The computer-controlled grout levelling system was used to level the differential settlement of the structure.
20 injection ports were installed through the concrete foundations, down to the top of the Jet-Crete columns, where the high mobility grout was introduced.
It took 10 working days to set up, install the 22 columns and then remove the Jet-Crete equipment.
A further 10 working days were required to install the JOG Computer-Controlled Grouting levelling equipment, level the building back to the agreed lift requirement and then remove the equipment.
The building was brought back exactly as required with the foundation ground greatly strengthened to better protect the structure from future seismic activity.
Resources
Download a pdf version of this project here
Apartment Building Subsidence Remediated
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Warehouse Floor Raised and Re-levelled
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