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Measurement of the tensile strength of organic soft rock


Tolooiyan, A and Mackay, R and Xue, J, Measurement of the tensile strength of organic soft rock, Geotechnical Testing Journal, 37, (6) pp. 1-11. ISSN 1945-7545 (2014) [Refereed Article]


Copyright Statement

Copyright 2014 ASTM Internationa

DOI: doi:10.1520/GTJ20140028


Understanding all potential slope failure mechanisms is a pre-requisite for predicting the likelihood of batter movements during excavation in open cut mines. The tensile behavior of soils and rocks may be a significant contributor to a slope failure and must be known in order to quantify the risks of slope failure. The contribution can be particularly significant for Intermediate Geotechnical Materials (IGMs) that possess characteristics of both soils and rocks and where the failure mechanisms are complex due to the interplay between ductile and brittle behavior. Brown coal is such an intermediate geotechnical material. Recent batter movements in the brown coal mines in the Latrobe Valley, Australia have raised doubts about the current understanding of the mechanisms of slope failure in this material. Research is underway to re-evaluate all properties of the brown coal applicable to slope failure. This paper describes the investigation of brown coal tensile strength. There are alternative test methods available to determine the tensile behavior of materials, including direct tensile tests, beam bending tests and Brazilian compression tests. The applicability of each test method is material dependent and, as such, it is necessary to confirm the validity of the methods for each material. Beam bending tests have achieved mixed results for both rocks and IGMs previously. Thus, the present work has explored only the use of Direct tensile and Brazilian test methods. Both methods were implemented using a modified direct shear apparatus and valid test procedures for both test methods were developed. Each test procedure has been verified by Finite Element Modelling (FEM) using ABAQUS 6.12.1 FEM code. The results from the laboratory test methods are in good agreement and show that brown coal is a predominantly brittle material with a peak tensile strength slightly greater than 100 kPa. The finite element analyses confirm that non-uniformity of the tensile stresses during sample loading tends to lead to the underestimation of tensile strength for both tests, but the Brazilian test has less bias for brown coal. It is observed that the rate of loading of low stiffness, low permeability, and saturated samples in the Brazilian test is an important test design parameter for the accurate determination of tensile strength of IGMs in the laboratory.

Item Details

Item Type:Refereed Article
Keywords:tensile strength, intermediate geotechnical material, laboratory testing, geotechnical modeling, brown coal
Research Division:Engineering
Research Group:Civil engineering
Research Field:Civil geotechnical engineering
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in engineering
UTAS Author:Tolooiyan, A (Dr Ali Tolooiyan)
ID Code:129467
Year Published:2014
Web of Science® Times Cited:19
Deposited By:Engineering
Deposited On:2018-11-30
Last Modified:2019-03-26
Downloads:110 View Download Statistics

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