Estimating the geotechnical properties of heterogeneous rock masses such as flysch

doi:10.1007/S100640000090

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Estimating the geotechnical properties of heterogeneous rock masses such as flysch

Journal Article•DOI•

Estimating the geotechnical properties of heterogeneous rock masses such as flysch

Paul Marinos¹, Evert Hoek•Institutions (1)

National Technical University of Athens¹

01 Jul 2001-Bulletin of Engineering Geology and the Environment (Springer-Verlag)-Vol. 60, Iss: 2, pp 85-92

TL;DR: In this paper, a methodology for estimating the Geological Strength Index and the rock mass properties for flysch formations is presented, which is used for the design of tunnels and slopes in heterogeneous rock masses.

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Abstract: The design of tunnels and slopes in heterogeneous rock masses such as flysch presents a major challenge to geologists and engineers. The complex structure of these materials, resulting from their depositional and tectonic history, means that they cannot easily be classified in terms of widely used rock mass classification systems. A methodology for estimating the Geological Strength Index and the rock mass properties for these geological formations is presented in this paper.

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Citations

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Hoek-brown failure criterion - 2002 edition

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Evert Hoek, Carlos Carranza-Torres, Brent Corkum

01 Jan 2002

TL;DR: The Hoek-Brown failure criterion for rock masses is widely accepted and has been applied in a large number of projects around the world as discussed by the authors, however, there are some uncertainties and inaccuracies that have made the criterion inconvenient to apply and to incorporate into numerical models and limit equilibrium programs.

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Abstract: The Hoek-Brown failure criterion for rock masses is widely accepted and has been applied in a large number of projects around the world. While, in general, it has been found to be satisfactory, there are some uncertainties and inaccuracies that have made the criterion inconvenient to apply and to incorporate into numerical models and limit equilibrium programs. In particular, the difficulty of finding an acceptable equivalent friction angle and cohesive strength for a given rock mass has been a problem since the publication of the criterion in 1980. This paper resolves all these issues and sets out a recommended sequence of calculations for applying the criterion. An associated Windows program called "RocLab" has been developed to provide a convenient means of solving and plotting the equations presented in this paper.

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1,628 citations

Gsi: A Geologically Friendly Tool For Rock Mass Strength Estimation

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Paul Marinos¹, Evert Hoek•Institutions (1)

National Technical University of Athens¹

19 Nov 2000

TL;DR: In this article, a review of the estimation of rock mass strength properties through the use of GSI is presented and a discussion is given regarding the ranges of the Geological Strength Index for typical rock masses with specific emphasis to heterogeneous rock masses.

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Abstract: This paper presents a review of the estimation of rock mass strength properties through the use of GSI The GSI classification system greatly respects the geological constraints that occur in nature and are reflected in the geological information A discussion is given regarding the ranges of the Geological Strength Index for typical rock masses with specific emphasis to heterogeneous rock masses

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553 citations

Journal Article•DOI•

The Hoek–Brown failure criterion and GSI – 2018 edition

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Evert Hoek, Edwin T. Brown

01 Jun 2019-Journal of rock mechanics and geotechnical engineering

TL;DR: The Hoek-Brown criterion was introduced in 1980 to provide input for the design of underground excavations in rock as mentioned in this paper, and it has been applied in many projects around the world.

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Abstract: The Hoek–Brown criterion was introduced in 1980 to provide input for the design of underground excavations in rock. The criterion now incorporates both intact rock and discontinuities, such as joints, characterized by the geological strength index (GSI), into a system designed to estimate the mechanical behaviour of typical rock masses encountered in tunnels, slopes and foundations. The strength and deformation properties of intact rock, derived from laboratory tests, are reduced based on the properties of discontinuities in the rock mass. The nonlinear Hoek–Brown criterion for rock masses is widely accepted and has been applied in many projects around the world. While, in general, it has been found to provide satisfactory estimates, there are several questions on the limits of its applicability and on the inaccuracies related to the quality of the input data. This paper introduces relatively few fundamental changes, but it does discuss many of the issues of utilization and presents case histories to demonstrate practical applications of the criterion and the GSI system.

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419 citations

Journal Article•DOI•

The geological strength index: applications and limitations

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Vasileios Marinos¹, Paul Marinos¹, Evert Hoek•Institutions (1)

National Technical University of Athens¹

02 Feb 2005-Bulletin of Engineering Geology and the Environment

TL;DR: The geological strength index (GSI) is a system of rock-mass characterization that has been developed in engineering rock mechanics to meet the need for reliable input data, particularly those related to rock mass properties required as inputs into numerical analysis or closed form solutions for designing tunnels, slopes or foundations in rocks as mentioned in this paper.

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Abstract: The geological strength index (GSI) is a system of rock-mass characterization that has been developed in engineering rock mechanics to meet the need for reliable input data, particularly those related to rock-mass properties required as inputs into numerical analysis or closed form solutions for designing tunnels, slopes or foundations in rocks. The geological character of rock material, together with the visual assessment of the mass it forms, is used as a direct input to the selection of parameters relevant for the prediction of rock-mass strength and deformability. This approach enables a rock mass to be considered as a mechanical continuum without losing the influence geology has on its mechanical properties. It also provides a field method for characterizing difficult-to-describe rock masses. After a decade of application of the GSI and its variations in quantitative characterization of rock mass, this paper attempts to answer questions that have been raised by the users about the appropriate selection of the index for a range of rock masses under various conditions. Recommendations on the use of GSI are given and, in addition, cases where the GSI is not applicable are discussed. More particularly, a discussion and suggestions are presented on issues such as the size of the rock mass to be considered, its anisotropy, the influence of great depth, the presence of ground water, the aperture and the infilling of discontinuities and the properties of weathered rock masses and soft rocks.

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415 citations

Cites methods from "Estimating the geotechnical propert..."

...1) (Hoek et al. 1998; Marinos and Hoek 2000, 2001)....
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...A GSI chart for flysch has been published in Marinos and Hoek (2001) and is reproduced in Fig....
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...2 (Marinos and Hoek 2001)....
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Predicting tunnel squeezing problems in weak heterogeneous rock masses

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Evert Hoek, Paul Marinos

01 Jan 2000

300 citations

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References

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Open Access

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Journal Article•DOI•

Practical estimates of rock mass strength

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Evert Hoek, Edwin T. Brown¹•Institutions (1)

University of Queensland¹

01 Dec 1997-International Journal of Rock Mechanics and Mining Sciences

TL;DR: This paper summarises the interpretation of the Hoek-Brown failure criterion which has been found to work best in dealing with practical engineering problems.

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2,813 citations

"Estimating the geotechnical propert..." refers background or methods in this paper

...The Geological Strength Index (GSI) was introduced by Hoek, Kaiser and Bawden (1995), Hoek and Brown (1997) and extended by Hoek, Marinos and Benissi (1998)....
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...The procedure making these estimates has been described in detail by Hoek and Brown (1997) it will not be repeated here....
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...A table listing such a qualitative description is given in Table 1, based on Hoek and Brown (1997)....
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...For tunnels at depths of greater than 30 m, the rock mass surrounding the tunnel is confined and its properties are calculated on the basis of a minor principal stress or confining pressure σ3 up to 0.25 σci, in accordance with the procedure defined by Hoek and Brown (1997)....
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...Estimation of rock mass properties One of the most widely used criteria for estimating rock mass properties is that proposed by Hoek and Brown (1997) and this criterion, with specific adaptations to heterogeneous rock masses such as flysch, is briefly summarised in the following text....
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Book•

Rock characterization, testing & monitoring: ISRM suggested methods

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Edwin T. Brown

01 Jan 1981

1,273 citations

"Estimating the geotechnical propert..." refers background in this paper

...* Grade according to Brown (1981)....
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...P is the load on the points and D is the distance between the points (Brown, 1981)....
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Book•

Support of underground excavations in hard rock

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Evert Hoek, Peter K. Kaiser, W.F. Bawden

01 Jan 1995

TL;DR: In this paper, a reference record was created on 2004-09-07, modified on 2016-08-08 and used for the purpose of Dimensionnement Classification and Excavation.

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Abstract: Keywords: Dimensionnement ; Classification ; Excavation ; Ouvrages souterrains ; Contrainte ; Ouvrages de soutenement Reference Record created on 2004-09-07, modified on 2016-08-08

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1,064 citations

Rock characterization testing and monitoring

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Edwin T. Brown

01 Jan 1981

TL;DR: The Mecanique des roches Reference Record was created on 2004-09-07, modified on 2016-08-08 as mentioned in this paper, and it was updated in 2016.

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Abstract: Keywords: Mecanique des roches Reference Record created on 2004-09-07, modified on 2016-08-08

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595 citations

"Estimating the geotechnical propert..." refers background or methods in this paper

...The Geological Strength Index (GSI) was introduced by Hoek, Kaiser and Bawden (1995), Hoek and Brown (1997) and extended by Hoek, Marinos and Benissi (1998). A chart for estimating the GSI for Flysch is presented in Table 3....
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...The Geological Strength Index (GSI) was introduced by Hoek, Kaiser and Bawden (1995), Hoek and Brown (1997) and extended by Hoek, Marinos and Benissi (1998)....
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...25 σci, in accordance with the procedure defined by Hoek and Brown (1997)....
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...The procedure making these estimates has been described in detail by Hoek and Brown (1997) it will not be repeated here....
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...* Grade according to Brown (1981). ** Point load tests on rocks with a uniaxial compressive strength below 25 MPa are likely to yield highly ambiguous results....
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Journal Article•DOI•

Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses. The case of the Athens Schist Formation

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E. Hoek¹, Paul Marinos², M. Benissi•Institutions (2)

IBM¹, National Technical University of Athens²

01 Sep 1998-Bulletin of Engineering Geology and the Environment

TL;DR: In this article, the applicability of the GSI classification system to these highly heterogeneous and anisotropic metasedimentary rock masses has been discussed and an extension to account for the foliated or laminated weak rocks in the lower range of its applicability is proposed.

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Abstract: The Athens Schist Formation includes a wide variety of metasedimentary rocks, varying from strong or medium strong rocks such as sericite metasandstone, limestone, greywacke, sericite schist through to weak rocks such as metasiltstone, clayey and silty shale and phyllite. The overall rock mass is highly heterogeneous and anisotropic owing to the combined effect of advanced weathering and severe tectonic stressing that gave rise to intense folding and shearing followed by extensional faulting, which resulted in highly weathered rock masses and numerous shear and/or mylonite zones with distinct downgraded engineering properties. This paper is focused on the applicability of the GSI classification system to these highly heterogeneous rock masses and proposes an extension of the GSI system to account for the foliated or laminated weak rocks in the lower range of its applicability.

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393 citations