Performance evaluation of existing surface excavation assessment methods on weathered sedimentary rock

Maybelle Liang, Edy Tonnizam Mohamad, Ibrahim Komoo, Ma Chau-Khun

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

This paper is intended as a contribution to the discussion of the overview of existing excavatability assessments and their reliability in assessing the state of tropically weathered rocks, specifically in Nusajaya, Johor, Malaysia. For this purpose, case studies were conducted on sedimentary rock masses of the Jurong formation, located in Nusajaya, Johor. The existing available rock mass excavatability assessments were first critically reviewed. Three case studies were then conducted in order to assess the performance of surface excavatability in these sedimentary rock masses by practical excavation tests on site. Comparisons were then made between the assessments of those assessors and that obtained through the practical excavation test. The conclusions made in the paper about the results of the study show many divergent opinions among the assessors. It emphasizes the limitations of existing available assessments in predicting the excavatability of tropically weathered rock masses. Further complication may arise in sedimentary rock masses where different layers of rock are interbedding, producing different weathering profiles. In view of these, a simpler graphical method, which considers only two parameters, namely point load strength and spacing of surface discontinuities, was introduced to overcome the problems, thus might be misjudged during early excavation assessment. This subjectivity becomes more important as the heterogeneity of a rock mass increases with increasing interbedding and inherent anisotropy of the rock material, giving rise to quite different evaluations, even for a rock with the same state of weathering. Most of the existing excavatability assessment methods are found to be less reliable because nature, lithology and weathering state at various rock mass layers is not being taken into account. A more practical and appropriate excavatability assessment method is thus required to economically assess the tropically weathered sedimentary rock during the preliminary stage.

Original languageEnglish
JournalBulletin of Engineering Geology and the Environment
DOIs
Publication statusAccepted/In press - 22 Jul 2015

Fingerprint

Sedimentary rocks
assessment method
Excavation
sedimentary rock
excavation
Rocks
rock
Weathering
weathering
weathering profile
graphical method
Lithology
evaluation
discontinuity
lithology
spacing
Anisotropy
anisotropy

Keywords

  • Excavatability assessment
  • Interbedding
  • Sandstone
  • Sedimentary rock
  • Shale
  • Weathering
  • Wet tropical

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geology

Cite this

Performance evaluation of existing surface excavation assessment methods on weathered sedimentary rock. / Liang, Maybelle; Mohamad, Edy Tonnizam; Komoo, Ibrahim; Chau-Khun, Ma.

In: Bulletin of Engineering Geology and the Environment, 22.07.2015.

Research output: Contribution to journalArticle

@article{b7ffebfa455a46b9b1d3339d8f26e2e3,
title = "Performance evaluation of existing surface excavation assessment methods on weathered sedimentary rock",
abstract = "This paper is intended as a contribution to the discussion of the overview of existing excavatability assessments and their reliability in assessing the state of tropically weathered rocks, specifically in Nusajaya, Johor, Malaysia. For this purpose, case studies were conducted on sedimentary rock masses of the Jurong formation, located in Nusajaya, Johor. The existing available rock mass excavatability assessments were first critically reviewed. Three case studies were then conducted in order to assess the performance of surface excavatability in these sedimentary rock masses by practical excavation tests on site. Comparisons were then made between the assessments of those assessors and that obtained through the practical excavation test. The conclusions made in the paper about the results of the study show many divergent opinions among the assessors. It emphasizes the limitations of existing available assessments in predicting the excavatability of tropically weathered rock masses. Further complication may arise in sedimentary rock masses where different layers of rock are interbedding, producing different weathering profiles. In view of these, a simpler graphical method, which considers only two parameters, namely point load strength and spacing of surface discontinuities, was introduced to overcome the problems, thus might be misjudged during early excavation assessment. This subjectivity becomes more important as the heterogeneity of a rock mass increases with increasing interbedding and inherent anisotropy of the rock material, giving rise to quite different evaluations, even for a rock with the same state of weathering. Most of the existing excavatability assessment methods are found to be less reliable because nature, lithology and weathering state at various rock mass layers is not being taken into account. A more practical and appropriate excavatability assessment method is thus required to economically assess the tropically weathered sedimentary rock during the preliminary stage.",
keywords = "Excavatability assessment, Interbedding, Sandstone, Sedimentary rock, Shale, Weathering, Wet tropical",
author = "Maybelle Liang and Mohamad, {Edy Tonnizam} and Ibrahim Komoo and Ma Chau-Khun",
year = "2015",
month = "7",
day = "22",
doi = "10.1007/s10064-015-0771-4",
language = "English",
journal = "Bulletin of Engineering Geology and the Environment",
issn = "1435-9529",
publisher = "Springer Verlag",

}

TY - JOUR

T1 - Performance evaluation of existing surface excavation assessment methods on weathered sedimentary rock

AU - Liang, Maybelle

AU - Mohamad, Edy Tonnizam

AU - Komoo, Ibrahim

AU - Chau-Khun, Ma

PY - 2015/7/22

Y1 - 2015/7/22

N2 - This paper is intended as a contribution to the discussion of the overview of existing excavatability assessments and their reliability in assessing the state of tropically weathered rocks, specifically in Nusajaya, Johor, Malaysia. For this purpose, case studies were conducted on sedimentary rock masses of the Jurong formation, located in Nusajaya, Johor. The existing available rock mass excavatability assessments were first critically reviewed. Three case studies were then conducted in order to assess the performance of surface excavatability in these sedimentary rock masses by practical excavation tests on site. Comparisons were then made between the assessments of those assessors and that obtained through the practical excavation test. The conclusions made in the paper about the results of the study show many divergent opinions among the assessors. It emphasizes the limitations of existing available assessments in predicting the excavatability of tropically weathered rock masses. Further complication may arise in sedimentary rock masses where different layers of rock are interbedding, producing different weathering profiles. In view of these, a simpler graphical method, which considers only two parameters, namely point load strength and spacing of surface discontinuities, was introduced to overcome the problems, thus might be misjudged during early excavation assessment. This subjectivity becomes more important as the heterogeneity of a rock mass increases with increasing interbedding and inherent anisotropy of the rock material, giving rise to quite different evaluations, even for a rock with the same state of weathering. Most of the existing excavatability assessment methods are found to be less reliable because nature, lithology and weathering state at various rock mass layers is not being taken into account. A more practical and appropriate excavatability assessment method is thus required to economically assess the tropically weathered sedimentary rock during the preliminary stage.

AB - This paper is intended as a contribution to the discussion of the overview of existing excavatability assessments and their reliability in assessing the state of tropically weathered rocks, specifically in Nusajaya, Johor, Malaysia. For this purpose, case studies were conducted on sedimentary rock masses of the Jurong formation, located in Nusajaya, Johor. The existing available rock mass excavatability assessments were first critically reviewed. Three case studies were then conducted in order to assess the performance of surface excavatability in these sedimentary rock masses by practical excavation tests on site. Comparisons were then made between the assessments of those assessors and that obtained through the practical excavation test. The conclusions made in the paper about the results of the study show many divergent opinions among the assessors. It emphasizes the limitations of existing available assessments in predicting the excavatability of tropically weathered rock masses. Further complication may arise in sedimentary rock masses where different layers of rock are interbedding, producing different weathering profiles. In view of these, a simpler graphical method, which considers only two parameters, namely point load strength and spacing of surface discontinuities, was introduced to overcome the problems, thus might be misjudged during early excavation assessment. This subjectivity becomes more important as the heterogeneity of a rock mass increases with increasing interbedding and inherent anisotropy of the rock material, giving rise to quite different evaluations, even for a rock with the same state of weathering. Most of the existing excavatability assessment methods are found to be less reliable because nature, lithology and weathering state at various rock mass layers is not being taken into account. A more practical and appropriate excavatability assessment method is thus required to economically assess the tropically weathered sedimentary rock during the preliminary stage.

KW - Excavatability assessment

KW - Interbedding

KW - Sandstone

KW - Sedimentary rock

KW - Shale

KW - Weathering

KW - Wet tropical

UR - http://www.scopus.com/inward/record.url?scp=84937714710&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84937714710&partnerID=8YFLogxK

U2 - 10.1007/s10064-015-0771-4

DO - 10.1007/s10064-015-0771-4

M3 - Article

AN - SCOPUS:84937714710

JO - Bulletin of Engineering Geology and the Environment

JF - Bulletin of Engineering Geology and the Environment

SN - 1435-9529

ER -