REVIEW OF ROCK STRENGTH CRITERIA (original) (raw)
Related papers
A Unified Strength criterion for rock material
A non-linear Unified Strength criterion for rock material is presented. It is the development of the Unified Strength Theory (in: M. Jono, T. Inoue (Eds.), Mechanical Behaviour of Materials-VI (ICM-6), Pergamon, Oxford, 1991, pp. 841-846) and the modification of the Hoek-Brown strength criterion (Underground Excavations in Rock, The Institution of Mining and Metallurgy, London, 1980). The effect of intermediate principal stress on rock strength is considered in the non-linear Unified Strength criterion. The
Evaluating elastic-plastic behaviour of rock materials using hoek-brown failure criterion
Journal of Civil Engineering and Management, 2012
As a matter of fact, the failure criteria only predict failure's initiation in materials. And, in order to predict postyield behaviour of materials, a much complicated formulation for stress-strain relationship is required, which we know as plasticity theory. For instance, these formulations are developed based on Mohr-Coulomb criterion for soils and Drucker-Prager criterion for concrete. According to a majority of rock mechanics researchers, the empirical and experimental Hoek-Brown failure criterion is one of the well-progressed and suitable criteria, which can efficiently predict the rock failure initiation under different stress states for various types of intact rocks and rock masses. In this article, according to the suggestion by Heok explained in his paper of 1997, this rugged mentioned criterion is considered as a yield criterion and the elastic-perfect plastic behaviour of rock masses is determined using calculating material constitutive matrix's arrays in terms of Hoek-Brown's material constants and mechanical characteristics of rock materials in the general stress space, considering associated flow rule.
A complement to Hoek-Brown failure criterion for strength prediction in anisotropic rock
Geomechanics and …, 2011
In this paper, a complement to the Hoek-Brown criterion is proposed in order to derive the strength of anisotropic rock from strength of the corresponding truly intact rock. The complement is a decay function, which unlike other modifications or suggestions made in the past, is multiplied to the function of the original Hoek-Brown failure criterion for intact rock. This results in a combined and extended form of the criterion which describes the strength of anisotropic rock as a varying fraction of the corresponding truly intact rock strength. Statistical procedures and in particular regression analyses were conducted into data obtained in experiments conducted in the current research program and those collected from the literature in order to define the Hoek-Brown's criterion complement. The complement function was best described by a simple polynomial including only three constants to be empirically evaluated. Further investigations also showed that these constants can be related to the other readily available parameters of rock material which further facilitate determining the constants. A great and prime advantage of the proposed complement is that it is mathematically simple including the least possible number of empirical constants which are easily estimated with minimum experimental effort. Moreover, proposed concept does not suggests any change to the original Hoek-Brown criterion itself or its constants and serves whenever anisotropy does exist in the rock. This further implies on the possibility of using any other failure criterion for intact rock in conjunction with the compliment to reach the strength of anisotropic rock.
Variation of the Intrinsic Rock Properties on Hoek-Brown Failure Criterion Parameters
Rudarsko-geološko-naftni zbornik
The Hoek-Brown (H-B) criterion is one of the most commonly used rock failure criteria in recent years. This criterion includes a constant parameter called mi which is a fundamental parameter for estimating rock strength. Due to the importance of the mi parameter in the H-B criterion, it is necessary to conduct comprehensive studies on various aspects of the effect of this parameter on the behavior of rocks. Therefore, in this study, using numerical simulation of the Triaxial Compressive Strength (TCS) tests in PFC-2D code, the effects of microscopic properties of different rocks on the H-B parameter mi have been studied. Based on the results of this study, it was found that the effects of micro-parameters on the H-B parameter mi can be different depending on the type of rock, however this parameter has an inverse relationship to the micro-parameters of bond tensile strength and bond fraction of the rocks. Also, the mi parameter increases with an increase in the micro-parameters of t...
2022
Defining the practical and proper rock failure criteria plays the most significant role in analysis and design in rock mechanics and rock engineering. Up to now, several failure criterions have been proposed for brittle rocks. Among them, Hoek-Brown failure criterion has received much attention and applied among the others for brittle rocks. The goal of this paper is to investigate the applicability of newly semi-empirical developed failure criterion inspired by Hoek-Brown failure criteria. To fulfil this aim, different triaxial test data from literature were selected and analysed for different rock types. Our obtained results prove the validity of recently proposed formulation for different investigated rock types.
2014
Abstract- In recent decades several empirical criteria have been presented, in order to simulate the triaxial behavior of rock samples. These factors have mostly been associated with some limitations, because of the natural complexity in rock sample’s behavior in deformation and physical form. Some of these parameters are appropriate for a specific type of rock or special condition in laboratory. By comparison with other parameters, although Bieniawski, Ramamurthy and Hoek criteria show minimal limitations, but according to this paper, they are not accurate enough in correlation with the results of the tests. In this paper a new empirical criteria is introduced and compared to the three mentioned criteria and as a result, the advantages of this newly introduced parameter in correlation with the test results are interpreted.
2013
In recent decades several empirical criteria have been presented, in order to simulate the triaxial behavior of rock samples. These factors have mostly been associated with some limitations, because of the natural complexity in rock sample's behavior in deformation and physical form. Some of these parameters are appropriate for a specific type of rock or special condition in laboratory. By comparison with other parameters, although Bieniawski, Ramamurthy and Hoek criteria show minimal limitations, but according to this paper, they are not accurate enough in correlation with the results of the tests. In this paper a new empirical criteria is introduced and compared to the three mentioned criteria and as a result, the advantages of this newly introduced parameter in correlation with the test results are interpreted.
A Simplified Failure Criterion for Intact Rocks Based on Rock Type and Uniaxial Compressive Strength
The uniaxial compressive strength (UCS) of intact rock, which can be estimated using relatively straightforward and cost-effective techniques, is one of the most practical rock properties used in rock engineering. Thus, constitutive laws to represent the strength and behavior of (intact) rock frequently use it, along with additional intrinsic rock properties. Although triaxial tests can be employed to obtain best-fit failure criterion parameters that provide best strength predictions, they are more expensive and require time-consuming procedures; as a consequence, they are often not readily available at early stages of a project. Based on the analysis of an extensive triaxial test database for intact rocks, we propose a simplified empirical failure criterion in which rock strength at failure is expressed in terms of confining stress and UCS, with a new parameter which can be directly estimated from the UCS for a specified rock type in the absence of triaxial test data. Performance of the proposed failure criterion is then tested for validation against experimental data for eight rock types. The results show that strengths of intact rock estimated by the proposed failure criterion are in good agreement with experimental test data, with small discrepancies between estimated and measurements strengths. Therefore, the proposed criterion can be useful for preliminary (triaxial) strength estimation of intact rocks when triaxial tests data are not available.
A modified Hoek–Brown failure criterion for anisotropic intact rock
International Journal of Rock Mechanics and Mining Sciences, 2008
The Hoek-Brown criterion parameters (s ci , m i and s) are significantly influenced by the strength anisotropy of intact rock. In the present study, the criterion was modified by incorporating a new parameter (k b ) to account for the effect of strength anisotropy, thus being able to determine the strength of intact anisotropic rock under loading in different orientations of the plane of anisotropy. The range of the parameter (k b ) for the rocks tested has been analytically investigated by carrying out triaxial tests, in different orientations of the foliation plane. The proposed modification was studied for metamorphic rocks (gneiss, schist, marble), but could also be applied to other rock types exhibiting ''inherent'' anisotropy, e.g. sedimentary as well as igneous rocks. The proposed modified criterion is intended for use for prediction of strength of intact rock, but can also be extended to rock masses. r