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NZGS members and committee provide a significant amount of support to projects run by other organisations to help further the interests of the society and our members. The most significant of these are summarised here.

MBIE BSP Seismic Risk Work Programme

NZGS representative: Rick Wentz

Engineering NZ is managing this project for MBIE to implement the changes coming from the updated National Seismic Hazard Model into codes and practice. This comprises:

  • Project 1: To incorporate new hazard including geotechnical considerations into 1170.5 (excluding basin effects) focused on elastic design spectrum. Due late 2022.
  • Project 2: To overhaul VM4 (and possible creation of new verification method for slopes), reconsider limit states, and incorporate uncertainty from the National Seismic Hazard Model.

NZS 3604 update

NZGS management committee lead: Phil Robins

Core team: Sally Hargraves

Programme: Work ongoing, draft Q2/Q3 2025

NZGS have an interest in the latest update, specifically in the work item “Foundations on Expansive Soils and also Liquefaction-prone Soils“.  Sally Hargraves has been accepted on the review panel as the NZGS representative.  A meeting has been held with a number of technical experts and interested parties after which the following has been agreed:

Expansive Soils:  There is insufficient information currently for standard foundation solutions to be added to NZS 3604.  NZGS have volunteered to coordinate the development of a Practice Note (or similar guidance document) that sets out investigation techniques, laboratory testing and classification in the NZ setting, heavily utilising the existing AS 2890 where applicable.  It will also aim to include foundation design options for various classes of expansivity.  Over time some of this may be able to be included in a future update of NZS 3604.  The panel of experts gathered for the meeting have agreed to take part in the development of this Practice Note.

Liquefiable Soils:  It has been agreed that sites where liquefiable conditions are present are usually sufficiently complex to warrant consideration by a geotechnical professional.  As such, standard ‘acceptable’ foundation solutions will not be added to NZS 3604.  As there is already sufficient guidance regarding investigations, analysis and foundation design in general use (refer MBIE/NZGS Modules; also MfE Planning for Liquefaction document), additional guidance in this space is not required.  It is proposed that the foundation options presented in the Canterbury Guidance (for repairing and rebuilding houses post-earthquake) can be copied into a separate document as an Appendix to Module 4: Foundations.  Additional foundation options can be added for the most common scenarios that crop up around the rest of NZ such as additional options in the TC2/TC3 hybrid category and new options in a TC1/TC2 hybrid category.  The use of the term “Technical Category – TC” will be phased out in the new document as these are only applicable in the areas tested by earthquake shaking in the Canterbury region.