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(PDF) Intact rock strength | George Tsiambaos

The strength and deformation characteristics of intact rock are controlled by many factors including anisotropy, moisture content, and confining pressure. The data from this test can be used as input parameters for estimating both intact rock and rock mass strength using either the Mohr -Coulomb or Hoek -Brown (1980, 1988 failure criteria.

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Rock Strength (Shear strength, compressive strength, tensile …

1-F Rock Strength Rock Strength -Shear Strength Shear strength: a vital geomechanics measure, used for design Shearing is associated with: •Borehole instabilities, breakouts, failure •Reservoir shear and induced seismicity •Casing shear and well collapse

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HOW TO DESCRIBE ROCK MASS CHARACTERISTICS ON …

 · 3. Weathering Reduction of rock strength due to weathering will reduce the shear strength of discontinuities as well as reduce the shear strength of the rock mass due to the reduced strength of the intact rock. Weathering categories and grades are summarized in Table-2.

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Testing services, rockmass, geomechanics

The intact rock strength is commonly measured through indices such as Triaxial, uniaxial (UCS), point load testing and Brazilian tensile strength. Shear strength testing allows the determination of cohesion and frictional properties of the geological discontinuities.

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Intact Rock

The strength of the intact rock has been assessed as 55 MPa, and so a conservative value for the strength rating is 6. The excavation is situated at a depth of 200 m, and the rock mass is a mudstone.

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Chapter 4 Engineering Classification of Rock Materials

gest intact rock material is greatly weakened by the occurrence of closely spaced discontinuities. Material properties, however, tend to control the strength of the rock mass if discontinuities are widely spaced or if the intact rock material is inherently weak or

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METHODS TO QUANTIFY THE PARAMETERS APPLIED IN THE RMi

Fig. A3-1 Various strength classifications for intact rock (from Bieniawski, 1984) The uniaxial compressive strength can be determined directly by uniaxial compressive strength tests in the laboratory, or indirectly from point-load strength test (see Section 1.4.2).

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Estimating the Intact Rock Strength of a Rock Mass by Simple Means

Intact rock strength is mostly defined as the strength of the rock material between the discontinuities. Strength values used are often from laboratory unconfined compressive strength (UCS) tests. Problems caused by the definition of intact rock strength and

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ROCK STRENGTH: THE INTERRELATIONSHIP BETWEEN …

ROCK STRENGTH: THE INTERRELATIONSHIP BETWEEN STRENGTH INDICES FROM CRUSHED ROCK AGGREGATE AND INTACT ROCK This paper presents the results of a pilot study of various Scottish igneous rocks, which aimed to compare values of aggregate strength from different tests and the relevance of values obtained from intact rocks as indices of aggregate quality.

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Lecture 9 – Introduction to Rock Strength David Hart University of Wisconsin

strength of the rock T, since T implies tensile failure. MOHR-COULOMB Criterion-Tensile Stresses Case I: σ 2 and σ are both tensile, so M-C criterion does not apply. Specimen fails in tension when σ 2 = T. Case II: σ 2 is tensile, but σ is zero or larger, so ...

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International Society for Rock Mechanics CONTENT

(a) Classification and characterization of intact rock (i) Porosity, unit weight, water content, absorbtion (ii) Hardness, abrasivity (iii) Durability (iv) Point load strength index (v) BPI (vi) UCS and deformability (viii) Sound velocity (v p, v s) (ix) Permeability (b) Rock

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(PDF) Determination of Rock Strength and …

Determination of Rock Strength and Deformability of Intact Rocks G. P. Tziallas Postgraduate Student Department of Geotechnical Engineering, School of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechniou, 15780, Zografou, Athens, Greece Email: [email protected] G. Tsiambaos Associate Professor Department of Geotechnical Engineering, …

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HOW TO CLASSIFY ROCKS? (ENGINEERING …

 · This method of rock classification was introduced by Deer & Miller in the year 1996. Two parameters are considered while classifying rocks on this method, which are Uniaxial compressive strength Modulus of elasticity Step by Step Method to Classify Rock Based on Engineering Parameters) This method of rock classification consists of 3 steps, as given […]

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CLASSIFICATION // CHARACTERIZATION OF SOME ROCK FEATURES

Intact rock strength The uniaxial compressive strength of a rock material constitutes the highest strength limit of the rock mass of which it forms a part. It is determined in accordance with the standard laboratory procedures. For the purpose of rock mass

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Estimating Rock Mass Strength

σc = uniaxial compressive strength of the intact rock material, σ1 = major principal stress at failure, and σ3 = minor principal stress at failure. The uniaxial compressive strength for the rock mass, σc, rockmass, can be expressed by setting σ3 = 0 in Equation 2

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Lectures on Rock MechanicsLectures on Rock Mechanics

Intact RockIntact Rock • HtHeterogeneous • Anisotropic (soils less so) • Spatial variability (soils the same) ... Strength Ranges for some Common Rock Material Term Kg/cm 2 Schist, Silt stone Very Weak- VW < 70 VW-W, Sand Stone, Lime stone –VW-M ...

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Tensile Strength of Geological Discontinuities Including …

The tensile strength of these rock bridges of intact rock was calculated as 17.8 MPa assuming zero strength elsewhere. This compares to the measured Brazilian tensile strength (12.5 MPa) for the intact rock. This might reflect some internal cementation and

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Estimating the Intact Rock Strength of a Rock Mass by Simple …

Intact rock strength is mostly defined as the strength of the rock material between the discontinuities. Strength values used are often from laboratory unconfined compressive strength (UCS) tests. Problems caused by the definition of intact rock strength and ...

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Intact Rock

Intact Rock - an overview | ScienceDirect Topics

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8. STRENGTH OF SOILS AND ROCKS

Rock strength has been found to be size dependent because of the cracks and fissures that are often present in the material. This is illustrated from the results of tests on three rock types in Fig. 8.2. The size dependancy is also found to exist for stiff fissured clays, as illustrated in Fig. 8.3 for London clay.

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Intact Rock Material

The strength of the intact rock material should be obtained from rock cores in accordance with site conditions. The ratings based on both UCS (which is preferred) and point load strength index are given in Table 6.1. UCS may also be obtained from the point load ...

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Standard Test Method for Splitting Tensile Strength of Intact Rock …

Splitting Tensile Strength of Intact Rock Core Specimens1 This standard is issued under the fixed designation D 3967; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A

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(PDF) Strength of intact rock and rock masses

A regression analyis of the entire data base provides a model to allow the triaxial strength of an intact rock to be estimated from reliable measurement of its uniaxial tensile and compressive...

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8. STRENGTH OF SOILS AND ROCKS

Rock strength has been found to be size dependent because of the cracks and fissures that are often present in the material. This is illustrated from the results of tests on three rock types in Fig. 8.2. The size dependancy is also found to exist for stiff fissured ...

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INFLUENCE OF INTACT ROCK STRENGTH ON ROCK MASS …

The first intact rock sample was assigned a uniaxial compressive strength of 205 MPa and an elastic modulus of 104 GPa with the UCS and elastic modulus values of the other samples downgraded by 10% until the weakest sample had a UCS value of 121 MPa and an elastic modulus value of 61 GPa.

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Rock mass properties

which occur in the field. Many rocks show a significant strength decrease with increasing moisture content and tests on samples, which have been left to dry in a core shed for several months, can give a misleading impression of the intact rock strength.

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STRENGTH PROPERTIES OF ROCKS AND ROCK MASSES 1. …

In general, rock mass strength depends on the strength of intact rock and the strength of rock discontinuities. In general, compared to intact rock, a rock mass has reduced tensile strength (almost zero), and reduced shear strength especi ally along discontinuity

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Evaluation of rock mass strength criteria

= uniaxial tensile strength of intact rock σ tm = uniaxial tensile strength of the rock mass σ'' 3max = the upper limit of confining stress over which the relationship between Mohr-Coulomb and Hoek-Brown criteria are considered ...

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Measurement of Strength of Intact Rock in the …

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