On the Mechanical Behavior of Granite Material With Particular Emphasis on the Influence From Pre-Existing Cracks and Defects

Abstract

In this investigation, experiments were carried out in order to determine the mechanical properties of Bohus granite considering the influence from pre-existing cracks and defects. The experimental investigation aimed at a complete material characterization, for the purpose of mechanical analyses using advanced constitutive models, based on a variety of tests. In doing so, direct tensile and compression tests were performed to evaluate the stiffness and strength; quasi-oedometric tests were carried out in order to obtain the deviatoric and volumetric behavior of the material at different levels of hydrostatic pressure (up to 860 MPa); three-point bend tests were performed to evaluate the quasi-static strength of the rock and its distribution. Weibull statistics was then employed to describe the strength distribution. The intact specimens indicated a rather low scatter in the mechanical properties such as Young’s modulus and tensile strength. However, specimens with large initial defects behaved differently. The failure mechanism in these specimens was not as brittle as the intact ones. The crack was opened on the tensile surface of such specimens during the three-point bend test at an early stage during loading, as demonstrated by digital image correlation results.

On the Inelastic Mechanical Behavior of Granite: Study Based on Quasi-oedometric and Indentation Tests

“…The fragmentation response of quasi-brittle materials subjected to quasi-static (Q-S) or dynamic loadings has been widely studied in the literature (Price and Farmer 1979;Cook et al 1984;Vermeer and De Borst 1984;Detournay 1986;Pang and Goldsmith 1990;Liu et al 2002;Saksala 2011Saksala , 2013Zhao and Cai 2010;Saksala 2010;Wang et al 2011;Arzúa and Alejano 2013;Saadati et al 2014Saadati et al , 2016Saadati et al , 2018Tkalich et al 2016;Weddfelt et al 2017). Cook et al (Cook et al 1984) investigated the fracture process by performing Q-S indentation tests on rock samples using circular flat-bottomed indenters with different sizes.…”

“…The fragmentation response of Bohus granite was investigated by some of the present authors (Saadati et al 2014(Saadati et al , 2018. A combination of pressure dependent plasticity (i.e.…”

“…It was shown that the tensile strength increased from 8 MPa under Q-S conditions to 19 MPa in the dynamic case (Saadati et al 2016). Further, the size effect on the tensile strength of Bohus granite was investigated by performing three-point bend tests on specimens of different sizes and using the Weibull size effect and the concept of effective volume (Weibull 1952;Davies 1973;Hild and Marquis 1992), namely, the portion of the total volume that is subjected to a positive equivalent stress (Saadati et al 2018). Furthermore in indentation applications the effective volume was calculated for a semi-infinite medium loaded by a cylindrical indenter and using a probabilistic approach (Weddfelt et al 2017).…”

“…In the present work, the inelastic constitutive behavior of the material is investigated based on, in particular, quasi-oedometric compression tests performed in an earlier work (Saadati et al 2018). The results from those tests are used herein to obtain the dilation angle for hydrostatic pressure levels up to 750 MPa.…”

Experimental and numerical study of the damage process inRCbeam‐column sub‐assemblages during a progressive collapse scenario

“…The Denoual-Forquin-Hild (DFH) anisotropic damage model [37][38][39] has been employed in numerous studies to simulate the growth of macro-cracks in concrete structures subjected to impact loadings [40][41][42] or the fracturing process in a granite rock under percussive drilling 43 or subjected to spalling tests or edge-on impact tests. [43][44][45] The DFH damage model considers three damage variables (D 1 , D 2 , and D 3 ) that are used to model the loss of stiffness along the three orthogonal directions that define the three principal directions of the stress tensor. The strain tensor ε ii is related to the stress tensor Σ ii according to [37][38][39]…”