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Commercial Building Subsidence Remediated

warehouse roof

The Challenge

The task comprised of two main parts:

  • To re-level the large section which had subsided.
  • Treat the ground down at depth by filling any potential voids to minimise the potential of further settlement.

The two tasks were to be completed without delay or compromising the complex building and its occupants. All the works had to be carried out while the production and operation remain active in the building as business interruption was not an option.

What we did and achieved

JOG Computer Controlled Grouting levelling system was initially utilised to level correct the building. The fine precision and absolute control which the system provides allowed full correction without disturbance to the surrounding areas.

100 injection ports at no more than 40mm diameter were installed through the concrete foundation, where the high mobility grout was introduced. The maximum lift was 156mm with an average of 80mm. To allow real time lift data, a robotic survey station was established adjacent to the building collecting level data from the many survey prisms set up on the building exterior.

During the second phase, LPDG Low Pressure Deep Grout, was utilised to fill voids at depth without fracturing the cohesive soils of the compacted fill material. Injection rods were inserted in sections at 112 locations down to 6m. Grouting took place at 1m intervals starting from the bottom up. The grout was introduced at low designed pressures allowing voids to be filled without fracturing the soils or creating uplift.

The structure was re-levelled and voids filled successfully returning the building to design levels all while the building remained in occupation.

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