Journal Published Online: 16 August 2007
Volume 31, Issue 1

Reproducibility of Direct Shear Tests Conducted on Granular Backfill Materials

CODEN: GTJODJ

Abstract

Intra-laboratory and inter-laboratory testing was conducted to assess the bias, repeatability, and reproducibility of the shear strength of compacted granular backfill materials tested in direct shear using AASHTO T 236. Inter-laboratory testing was conducted by ten laboratories using four granular backfill materials. Triaxial compression tests were also conducted on the granular backfill materials to establish a reference friction angle (ϕ) for computing bias. Comparison of failure envelopes and friction angles from the intra-laboratory study showed that the test method is highly repeatable (ϕ±0.1°) when conducted in a single laboratory by a single operator using the same equipment. In contrast, data from the inter-laboratory study showed high variability in the failure envelopes and friction angles, with ϕ varying by as much as 18.2° for a given backfill. Analysis of the data from the inter-laboratory study showed that the reproducibility of direct shear tests on granular backfill is 8.8°. The bias in ϕ is −2.5° when area corrections are not applied and −1.5° when area corrections are applied.

Author Information

Bareither, Christopher
Geological Engineering, University of Wisconsin-Madison, Madison, WI
Benson, Craig
Geological Engineering, University of Wisconsin-Madison, Madison, WI
Edil, Tuncer
Geological Engineering, University of Wisconsin-Madison, Madison, WI
Pages: 11
Price: $25.00
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Stock #: GTJ100878
ISSN: 0149-6115
DOI: 10.1520/GTJ100878