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A bonded-particle model for rock

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Practical estimates of rock mass strength

The goal of this article is to revise several aspects of the well-known classification of landslides, developed by Varnes (1978). The primary recommendation is to modify the definition of landslide-forming materials, to provide compatibility with accepted geotechnical and geological terminology of rocks and soils. Other, less important modifications of the classification system are suggested, resulting from recent developments of the landslide science. The modified Varnes classification of landslides has 32 landslide types, each of which is backed by a formal definition. The definitions should facilitate backward compatibility of the system as well as possible translation to other languages. Complex landslides are not included as a separate category type, but composite types can be constructed by the user of the classification by combining two or more type names, if advantageous.

The Varnes classification of landslide types, an update

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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Hoek-brown failure criterion - 2002 edition

Volume changes of a granite, a marble, and an aplite were measured during deformation in triaxial compression at confining pressure of as much as 8 kb. Stress-volumetric strain behavior is qualitatively the same for these rocks and a wide variety of other rocks and concrete studied elsewhere. Volume changes are purely elastic at low stress. As the maximum stress becomes one-third to two-thirds the fracture stress at a given pressure, the rocks become dilatant; that is, volume increases relative to elastic changes. The magnitude of the dilatancy, with a few exceptions, ranges from 0.2 to 2.0 times the elastic volume changes that would have occurred were the rock simply elastic. The magnitude of the dilatancy is not markedly affected by pressure, for the range of conditions studied here.

For granite, the stress at which dilatancy was first detected was strongly time dependent; the higher the loading rate the higher the stress. Dilatancy, which represents an increase in porosity, was traced in the granite to open cracks which form parallel with the direction of maximum compression.

Dilatancy in the Fracture of Crystalline Rocks

This book deals with the geotechnical aspects of the design of underground openings for mining and civil engineering purposes. It contains a number of worked examples to assist the reader in applying the techniques described to his or her own problems. The data are presented under the following chapter headings: (1) planning considerations; (2) classification of rock masses; (3) geological data collection; (4) graphical presentation of geological data; (5) stresses around underground excavations; (6) strength of rock and rock masses; (7) underground excavation failure mechanisms; (8) underground excavation support design; (9) rockbolts, shotcrete and mesh; (10) blasting in underground excavations; (11) instrumentation. Several appendices deal with: isometric drawing charts, stresses around single openings, two-dimensional boundary element stress analysis, determination of material constants, underground wedge analysis, and conversion factors. A very extensive bibliography is included.

Underground excavations in rock

This book is concerned with the stability of rock slopes, with methods for assessing this stability and with techniques for improving the stability of slopes which are potentially dangerous. The geotechnical problems of rock slope design are discussed for the mining or civil engineer who is not a specialist in rock or soil mechanics; many work examples are included to assist in relating the techniques described to his own slope problems. Methods for the collection and interpretation of geological and groundwater information are presented and tests for the determination of relevant mechanical properties of rock are described.

Rock slope engineering

An empirical strength criterion for rocks and rock masses is proposed. The nonlinear criterion includes the uniaxial compressive strength of the intact rock material and introduces two dimensionless parameters, m and s. The parameter m varies with rock type, the angle of interblock or interparticle friction and the degree of block or particle interlock. The parameter s varies from 1.0 for intact rock material to zero for granular aggregates and depends on the interparticle tensile strength and the degree of interlock within the rock mass. For anisotropic rock, both m and s vary with the orientations of the planes of weakness to the principal stress directions. Approximate relationships between rock type, rock mass quality indices, and the rock mass strength parameters m and s, are presented. These relationships have been found useful in preliminary design calculations for slopes and underground excavations in jointed rock.

Evert Hoek

Papers

Practical estimates of rock mass strength

Underground excavations in rock

Hoek-brown failure criterion - 2002 edition

Rock slope engineering

Empirical Strength Criterion for Rock Masses