Mechanical behaviors of soft rocks based on the fractional thermal elastic-plastic theory

Li, H; Ma, B; Zhang, S; Sheng, D

Mechanical behaviors of soft rocks based on the fractional thermal elastic-plastic theory

Li, H Ma, B Zhang, S Sheng, D

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Publication Type:: Journal Article
Citation:: Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering, 2020, 39, (7), pp. 1311-1320
Issue Date:: 2020-07-01

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Field	Value	Language
dc.contributor.author	Li, H
dc.contributor.author	Ma, B
dc.contributor.author	Zhang, S
dc.contributor.author	Sheng, D https://orcid.org/0000-0002-1665-6931
dc.date.accessioned	2021-04-15T01:59:47Z
dc.date.available	2021-04-15T01:59:47Z
dc.date.issued	2020-07-01
dc.identifier.citation	Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering, 2020, 39, (7), pp. 1311-1320
dc.identifier.issn	1000-6915
dc.identifier.issn	1000-6915
dc.identifier.uri	http://hdl.handle.net/10453/148117
dc.description.abstract	Soft rocks have complex thermodynamic behaviors and their strength maybe increase or decrease with temperature. In this paper, the soft rocks were considered as heavily over-consolidated clays and their preconsolidation pressure was assumed to be the uniaxial compression strength. Based on the fractional thermal elastoplastic theory, a fractional sub-loading surface model for soft rocks considering the effects of temperature was proposed, which can decribe associated and non-associated flow rules without introducing the plastic potential. The analysis results show that the phenomena of heat-increase and heat-decrease are closely related to the angle of the plastic flow direction and the loading direction. Application of the non-associated flow rule in the undrained triaxial test results in that stress paths of soft rocks cross through the critical state line and finally reach the critical state, and the undrained shear strength of soft rocks will increase as temperature increases. On the other hand, the associated flow rule will do the opposite. In addition, the preconsolidation pressure of soft rocks will decrease as temperature increases, leading that the sub-loading surface is located outside the temperature loading surface in the p-q plane and that the overconsolidated ratio OCR is smaller than 1. Comparisons between the proposed model with test results indicate that soft rocks show the features of strain-softening and dilatancy, which can be captured by the proposed model, and that, increasing temperature will decrease the fragility of soft rocks as well as the dilatancy. Compared with the modified Cam-clay model, the proposed model introduces two extra parameters including the coefficient of linear expansion α and dilative related parameter m, which have clear physical meanings and can be determined through conventional tests directly. T
dc.language	en
dc.relation.ispartof	Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering
dc.relation.isbasedon	10.13722/j.cnki.jrme.2019.1243
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0913 Mechanical Engineering
dc.subject.classification	Geological & Geomatics Engineering
dc.title	Mechanical behaviors of soft rocks based on the fractional thermal elastic-plastic theory
dc.type	Journal Article
utslib.citation.volume	39
utslib.for	0913 Mechanical Engineering
utslib.for	0913 Mechanical Engineering
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
utslib.copyright.status	open_access	*
pubs.consider-herdc	false
dc.date.updated	2021-04-15T01:59:45Z
pubs.issue	7
pubs.publication-status	Published
pubs.volume	39
utslib.citation.issue	7

Abstract:

Soft rocks have complex thermodynamic behaviors and their strength maybe increase or decrease with temperature. In this paper, the soft rocks were considered as heavily over-consolidated clays and their preconsolidation pressure was assumed to be the uniaxial compression strength. Based on the fractional thermal elastoplastic theory, a fractional sub-loading surface model for soft rocks considering the effects of temperature was proposed, which can decribe associated and non-associated flow rules without introducing the plastic potential. The analysis results show that the phenomena of heat-increase and heat-decrease are closely related to the angle of the plastic flow direction and the loading direction. Application of the non-associated flow rule in the undrained triaxial test results in that stress paths of soft rocks cross through the critical state line and finally reach the critical state, and the undrained shear strength of soft rocks will increase as temperature increases. On the other hand, the associated flow rule will do the opposite. In addition, the preconsolidation pressure of soft rocks will decrease as temperature increases, leading that the sub-loading surface is located outside the temperature loading surface in the p-q plane and that the overconsolidated ratio OCR is smaller than 1. Comparisons between the proposed model with test results indicate that soft rocks show the features of strain-softening and dilatancy, which can be captured by the proposed model, and that, increasing temperature will decrease the fragility of soft rocks as well as the dilatancy. Compared with the modified Cam-clay model, the proposed model introduces two extra parameters including the coefficient of linear expansion α and dilative related parameter m, which have clear physical meanings and can be determined through conventional tests directly. T

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http://hdl.handle.net/10453/148117