Canterbury Technical Forum Meeting
5:40 pm – 7:20 pm, Tuesday 10 September 2013
Lecture Theatre E8, College of Engineering, University of Canterbury
The Forum meeting was chaired and summarised by Bruce Deam on behalf of the NZ Society for Earthquake Engineering.
Clive Anderson (Golder Associates) gave a brief update on the EQC foundation system trials of rapid impact compaction, rammed aggregate piers, low mobility grout compaction bulbs and horizontal mechanical mixing (see Sjoerd van Ballegooy's presentation to CTF Meeting 47). He indicated that the T-Rex testing was being carried out and that there would be blasting tests in October. He then introduced the guest presenter.
Dr Kord Wissmann, President and Chief Engineer of the US-based Geopier Foundation Company Inc, gave a comprehensive introduction to the Rammed Aggregate Pier (RAP) system. He began by outlining the other reconstruction choices commonly employed with a brief description of their merits and disadvantages. He indicated that there were many types of RAP but focused on the impact pier that is able to provide good control of the pier diameter and the quantity of the aggregate. He outlined the types of soils that were best (and least) improved along with the mechanics of the improvement, which he related to overconsolidation. Kord also explained why RAP wouldn't improve the factor of safety through drainage or attraction of shear stress. He concluded with some examples and an outline of their Denserpact system that can rapidly densify the top 3 or 6 metres of the soil. Kord's Presentation
Mike Stannard (Building and Housing, MBIE) introduced their recent Clarifications and updates to the guidance 'Repairing and rebuilding houses affected by the Canterbury earthquakes', with a further 16 answers to commonly asked questions, supplementary guidance on when a foundation plan is irregular enough to require specific design for use on TC3 residential sites, and a simplified procedure for assessing kinematic pile strains for TC3 residential sites. He also outlined the 5 year MBIE work programme to resolve 177 or the 189 Royal Commission recommendations. Mike's Presentation
John Hare (Holmes Consulting Group, SESOC Chair) described how some designers were incorrectly using reduced building design life to justify strengthening to less than the required percentage of New Building Standard. He also highlighted the need for Design Features Reports to be consistent with the geotechnical engineering recommendations (that should be obvious but is often inconsistent within consent applications). He also gave an update on the CCC progression toward risk-based consenting, which aims to improve building quality and consistency by having a Senior Engineering Advisory Panel review high risk projects early in the design process. John's Presentation
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