Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint

Cryptocrystalline flint is an extremely hard siliceous rock that is found in chalk formations. The chalk is frequently a prefered rock type, which in recent decades is often used as a host for underground rock caverns and tunnels in Europe and North America. A reliable estimation of the uniaxial com...

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Main Authors: Aliyu, Mohammed M., Shang, Junlong, Murphy, William, Lawrence, James Anthony, Collier, Rirchard, Kong, Fanmeng, Zhao, Z.
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/146947
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1469472021-03-15T06:30:22Z Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint Aliyu, Mohammed M. Shang, Junlong Murphy, William Lawrence, James Anthony Collier, Rirchard Kong, Fanmeng Zhao, Z. School of Civil and Environmental Engineering Nanyang Centre for Underground Space (NCUS) Engineering::Civil engineering Flint Uniaxial Compressive Strength Cryptocrystalline flint is an extremely hard siliceous rock that is found in chalk formations. The chalk is frequently a prefered rock type, which in recent decades is often used as a host for underground rock caverns and tunnels in Europe and North America. A reliable estimation of the uniaxial compressive strength (UCS) of the extremely strong flint, with an average UCS of about 600 MPa will provide guidance for a proper engineering design, where flint is encountered, thereby avoiding project progress delay, litigation as well as economic consequences. Conventional UCS measurement using core samples is cumbersome for flint due to the extreme strength and hardness of the rock, for which the core sample preparation process is often extremely difficult. In this study, the UCS prediction models of flints collected from the North-West Europe were developed and the validity of the developed models was investigated. A series of laboratory index tests (comprising the three-point-bending, point load, ultrasonic velocity, density, Shore hardness and Cerchar Abrasivity tests) were perfomed. The index test results were correlated with the UCS values previously determined in the laboratory using both cylindrical and cuboidal specimens to develop the UCS prediction models. Regression analysis of the UCS and the index test results was then performed to evaluate for any potential correlations that can be applied to estimate the UCS of the cryptocrystalline flint. Intensive validity and comparison studies were performed to assess the performance of the proposed UCS prediction models. This study showed that UCS of the tested flint is linearly correlated with its point load strength index, tensile strength and compressional velocity, and is parabolically correlated with its density. The present study also demonstrated that only a couple of the previously developed empirical UCS models for estimating UCS are suitable for flint, which should be used with care. Accepted version 2021-03-15T06:23:23Z 2021-03-15T06:23:23Z 2019 Journal Article Aliyu, M. M., Shang, J., Murphy, W., Lawrence, J. A., Collier, R., Kong, F. & Zhao, Z. (2019). Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint. International Journal of Rock Mechanics and Mining Sciences, 113, 310-321. https://dx.doi.org/10.1016/j.ijrmms.2018.12.002 1365-1609 https://hdl.handle.net/10356/146947 10.1016/j.ijrmms.2018.12.002 2-s2.0-85058630342 113 310 321 en International Journal of Rock Mechanics and Mining Sciences © 2018 Elsevier Ltd. All rights reserved. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Civil engineering
Flint
Uniaxial Compressive Strength
spellingShingle Engineering::Civil engineering
Flint
Uniaxial Compressive Strength
Aliyu, Mohammed M.
Shang, Junlong
Murphy, William
Lawrence, James Anthony
Collier, Rirchard
Kong, Fanmeng
Zhao, Z.
Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
description Cryptocrystalline flint is an extremely hard siliceous rock that is found in chalk formations. The chalk is frequently a prefered rock type, which in recent decades is often used as a host for underground rock caverns and tunnels in Europe and North America. A reliable estimation of the uniaxial compressive strength (UCS) of the extremely strong flint, with an average UCS of about 600 MPa will provide guidance for a proper engineering design, where flint is encountered, thereby avoiding project progress delay, litigation as well as economic consequences. Conventional UCS measurement using core samples is cumbersome for flint due to the extreme strength and hardness of the rock, for which the core sample preparation process is often extremely difficult. In this study, the UCS prediction models of flints collected from the North-West Europe were developed and the validity of the developed models was investigated. A series of laboratory index tests (comprising the three-point-bending, point load, ultrasonic velocity, density, Shore hardness and Cerchar Abrasivity tests) were perfomed. The index test results were correlated with the UCS values previously determined in the laboratory using both cylindrical and cuboidal specimens to develop the UCS prediction models. Regression analysis of the UCS and the index test results was then performed to evaluate for any potential correlations that can be applied to estimate the UCS of the cryptocrystalline flint. Intensive validity and comparison studies were performed to assess the performance of the proposed UCS prediction models. This study showed that UCS of the tested flint is linearly correlated with its point load strength index, tensile strength and compressional velocity, and is parabolically correlated with its density. The present study also demonstrated that only a couple of the previously developed empirical UCS models for estimating UCS are suitable for flint, which should be used with care.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Aliyu, Mohammed M.
Shang, Junlong
Murphy, William
Lawrence, James Anthony
Collier, Rirchard
Kong, Fanmeng
Zhao, Z.
format Article
author Aliyu, Mohammed M.
Shang, Junlong
Murphy, William
Lawrence, James Anthony
Collier, Rirchard
Kong, Fanmeng
Zhao, Z.
author_sort Aliyu, Mohammed M.
title Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
title_short Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
title_full Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
title_fullStr Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
title_full_unstemmed Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
title_sort assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint
publishDate 2021
url https://hdl.handle.net/10356/146947
_version_ 1695706186033135616