Event Organisation: NZGS

Presented by  Dr Simon Cox, Principal Scientist, GNS Science, Dunedin

 Dr Simon Cox will be discussing the initial findings from groundwater monitoring and spatial models for Dunedin.

Free registration  HERE

Join the New Zealand Geotechnical Society in their upcoming panel discussion – The role of a peer reviewer in geotechnical design.

Presented by Dr Rolando Orense
Associate Professor, University of Auckland

Pumice-rich soils are often encountered in many engineering projects and their geotechnical characterisation is very important. Due to the highly crushable nature of the pumice sand components, the applicability of current empirical correlations which have been derived from hard-grained sands needs investigation.

The presentation focuses on the findings of the research projects conducted at the University of Auckland (with the support of EQC, NHRP and QuakeCoRE) to characterize the pumice sand properties and the dynamic and liquefaction characteristics of natural pumiceous deposits through field testing, high- quality soil sampling and laboratory testing. Moreover, the procedure developed to quantify the pumice contents of soil samples based on the crushability feature of the materials is presented.

Finally, based on the results obtained to date, an empirical chart correlating shear wave velocity and cyclic resistance as a function of the soil’s pumice contents is proposed.

Presented by Mark Springer, Senior Lecturer, University of Canterbury
Recipient of the NZGS JW Ridley Geomechanics Paper Award

Pumice-rich deposits are found in a number of locations around the world, and in particular across large areas of the North Island of New Zealand. Pumice grains are commonly described as being lightweight, highly crushable, and vesicular in nature. These characteristics give rise to a unique set of behaviours under loading, and pumice-rich soils are highly problematic in terms of in situ characterisation in large part due to their crushability. The presence of pumice within a soil mixture has the potential to completely alter the stress–strain behaviour of these soils as well as require a different interpretation of results from commonly used site characterisation technique. It is therefore important to be able to determine quantitatively the percentage of pumice within a given soil deposit. This paper proposes a methodology based on a gravity separation of pumice-bearing mixtures with a heavy fluid. The application of themethod to artificial mixtures of fine pumice and non-pumiceous sands is shown to be sufficiently accurate for engineering purposes.

Mark obtained his PhD from the University of Cambridge, following research on the axial load distributions on piled foundations in
liquefiable soils using a geotechnical centrifuge. Since joining the CNRE department at the University of Canterbury, Mark has been
involved in a series of element testing projects on New Zealand soils, including the silty soils around Christchurch and more recently,
the pumice-rich deposits of the North Island. As a core part of this work, Mark has been trialling the use of the innovative gel-push
samplers developed by Kiso-Jiban consultants in Japan

KINDLY SPONSORED BY GEOTECHNICS AND THE UNIVERSITY OF WAIKATO