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Proficiency/Peer Review of Direct Shear and Index Testing Methods and Procedures

Proficiency/Peer Review of Direct Shear and Index Testing Methods and Procedures

MEMO
Date: 9 October 2014 Ref: 7505 / 7400 / 576-1
To: Trilab Pty Ltd
Attention: Col Purvis, Chris Channon, Chris Park, James Russell
Copy: Professor Stephen Fityus, The University of Newcastle
From: John Simmons
___________________________________________________________________________
Subject: INTERLAB PROFICIENCY TESTING REPORT: STOCKTON BEACH SAND PARTICLE SIZE DISTRIBUTION, PARTICLE SPECIFIC DENSITY, DRY SHEAR STRENGTH: DIRECT SHEAR APPARATUS

1. Introduction
The University of Newcastle has used locally available, well sorted Stockton Beach Sand as a
reference material for many research projects over a considerable period of time. Ajalloeian et.al
(1996) published a compilation of properties which has formed the basis for later comparison and
calibration tests.
Over the period 2012 to 2014, as part of a research project funded by the Australian Coal
Association Research Program (ACARP), a large direct shear machine (LDSM) was designed,
constructed, and operated for measuring the shear strength of coal mine spoil materials. Stockton
Beach Sand was used for a number of calibration tests, including comparisons of three different
shear box sizes of 300mm x 300mm and 720mm x 720mm (LDSM).
During 2014 some variations in LDSM test results were obtained when a different operator
undertook repeat calibration tests on Stockton Beach Sand. Because the LDSM design for
application of shear deformation differs in some respects from typical direct shear apparatus, it was
decided to seek an independent strength measurement to provide certainty about which of the two
LDSM calibration tests was most accurate.
Trilab Pty Ltd operates a large NATA-accredited testing facility in Brisbane, and was approached to
undertake independent testing of Stockton Beach Sand as an inter-laboratory proficiency testing
exercise. This report summarises the Trilab and University of Newcastle (UN) results for:

  • Particle size distribution (PSD);
  • Particle specific density (Gs);
  • Direct shear tests on sand placed as loosely as possible.