To ensure no heave or subsidence occurred, we surveyed the existing building prior to the project commencing and established trigger points to observe movement during the works. Quality control was implemented into the design plan, including daily mud balance testing of the grout mix and spoil returns, core sampling and cross-hole shear wave testing of completed columns.

Jet grout columns were constructed using GSI’s specialised SoilMec SM3 micro-piling jet grouting rig. Columns were distributed surrounding the failed well at depths near 15m BEGL. Each jet grout column had a design length of 7.5m from within the basement and up to 12.5m surrounding the building. Mix designs injected a cement application rate of 700 kg/m3.

GSI led the way with this high-profile, technically complex project, with their jet grouting expertise. Over the 128 days on-site, they constructed 107 jet grout columns, used almost 1,000 tonnes of cement, and completed work to the specified quality control standards.