Influence of nonlinearity and double elasticity on flexure of rock beams - I. Technical theory

Exadaktylos, GE; Vardoulakis, I; Kourkoulis, SK

dc.contributor.author	Exadaktylos, GE	en
dc.contributor.author	Vardoulakis, I	en
dc.contributor.author	Kourkoulis, SK	en
dc.date.accessioned	2014-03-01T01:16:39Z
dc.date.available	2014-03-01T01:16:39Z
dc.date.issued	2001	en
dc.identifier.issn	0020-7683	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14142
dc.subject	Elasticity	en
dc.subject	Nonlinearity	en
dc.subject	Rock beams	en
dc.subject	Theory	en
dc.subject.classification	Mechanics	en
dc.subject.other	Bending strength	en
dc.subject.other	Crystalline rocks	en
dc.subject.other	Elastic moduli	en
dc.subject.other	Elasticity	en
dc.subject.other	Friction	en
dc.subject.other	Microcracks	en
dc.subject.other	Poisson ratio	en
dc.subject.other	Strain	en
dc.subject.other	Stress analysis	en
dc.subject.other	Tensile strength	en
dc.subject.other	Tensile testing	en
dc.subject.other	Hooke's linear constitutive law	en
dc.subject.other	Rock mechanics	en
dc.subject.other	elasticity	en
dc.subject.other	flexure	en
dc.subject.other	nonlinearity	en
dc.subject.other	rock	en
dc.title	Influence of nonlinearity and double elasticity on flexure of rock beams - I. Technical theory	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0020-7683(00)00251-1	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0020-7683(00)00251-1	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	As a rule, solids display nonlinearity during loading in the relation between strains and stresses. Deviations from Hooke's linear constitutive law were also registered in the range of initial: small reads both in uniaxial compression and tension of crystalline rocks. Nonlinearity of strain in rocks is manifested primarily in the stress dependency of tangent or secant elasticity modulus and Poisson's ratio and is caused by closure, initiation, propagation and linkup of pre-existing and new microcracks, frictional sliding along cracks, growth of dislocations, etc. Many experimenters and standardization procedures assume that the dependence of the strain on the applied stress is linear and for practical calculations only two elasticity constants are used: the tangent or secant elasticity modulus at 50%, of the failure load in compression and Poisson's ratio at the same stress level. Apart from nonlinearity many rock types and concretes have quite different stress-strain relations in tension and compression. Yet direct tensile testing is seldom performed because of its many inherent difficulties. such unrecognized double elasticity and nonlinearity of rocks can invalidate a stress analysis, and in addition, produce a meaningless overestimate (or underestimate) of tensile strength based upon the modulus of rupture derived from a bending test. In Part I of the present study, it is shown that both double elasticity and nonlinearity have a profound effect on flexural strength of rocks as predicted by application of fundamental continuum damage mechanics relations and an appropriate technical theory. The proposed theory is validated in Part II of this work, in which an appropriate back-analysis procedure is suggested for the characterization of the mechanical properties of Dionysos marble in the uniaxial tension and compression regime from properly designed three-point bending tests. (C) 2001 Elsevier Science Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	International Journal of Solids and Structures	en
dc.identifier.doi	10.1016/S0020-7683(00)00251-1	en
dc.identifier.isi	ISI:000168594200011	en
dc.identifier.volume	38	en
dc.identifier.issue	22-23	en
dc.identifier.spage	4091	en
dc.identifier.epage	4117	en