Compressive strength of rocks - PetroWiki

 · Estimating compressive strength. General rock failure criterion can be reduced to a few parameters dependent on lithology (m) and the uniaxial compressive strength (C 0).Lithology is commonly derived during log analysis, so m may be estimated (Table 1).What is needed still is an initial measure of rock strength provided by C 0. C 0 can be estimated from porosity or sonic velocities, but …


if a rock mass is cut by directional joint sets , the rock mass strength is anisotropic. Rock mass strength is scale dependent and varies with the volume of rock under consideration. The modes of failure of intact rock are multiple. Rock can fail in tension, compression or shear.

Uniaxial Compressive Strength - an overview

The uniaxial compressive strength of a rock under static loading often decreases with an increasing temperature at which the rock has been heat-treated before strength testing. This conclusion is drawn from a great number of experiments [1,2,4,8,9,11,17–19].The higher the temperature is, the lower the strength. Some results for uniaxial compressive strength σ c and tensile strength σ t .


towards any other strength parameter. (Bishop, 1966). In the case of concrete, the compressive strength is the most commonly measured strength parameter and this is also true of rock specimens. For the uniaxial or unconfined compressive strength test a right circular cylinder of the

Lecture 9 – Introduction to Rock Strength David Hart

• The peak stress is the strength of the rock. – It may fail catastrophically if the load frame is “soft”. Example below is for a “stiff” frame. • The compressive strength of rock is a function of the confining pressure. • As the confining pressure increases so does the strength. Goodman, Intro to Rock …

Unconfined Compressive Strength Test of Rock

 · Unconfined Compressive Strength Test of Rock. This test method specifies the apparatus, instrumentation, and procedures for determining unconfined compressive strength of intact rock core specimens. This procedure is identical to ASTM D 2938 except that the cores are tested after cutting without grinding, and neoprene caps are used on the .

Chapter 4 Engineering Classification of Rock Materials

• hardness and unconfined compressive strength categories unit weight (dry) • unit weight (dry) • color • discrete rock particle size (use D 50 or cube root of the product of its three dimensions) (a) Rock unit identification The rock unit is the basic mapping unit for the rock …

Unconfined Compressive Strength Test of Rock

 · Unconfined Compressive Strength Test of Rock. This test method specifies the apparatus, instrumentation, and procedures for determining unconfined compressive strength of intact rock core specimens. This procedure is identical to …

compressive strength and the factor m in Hoek-Brown

i is the parameter for intact rock in the Hoek -Brown failure criterion for rock masses by Hoek et a l. (1998). Values in parenthesis have been estimated by Hoek et al (1992); values with question mark have been assumed 2) For clays the values of the uniaxial compressive strength is based on ISRM (1978), refer to Table 2.7.

Uniaxial Compressive Strength Determination of Rocks

 · The uniaxial compressive strength (UCS) is an important parameter for rock mass classification and rock engineering designs. This study proposes a novel method for predicting the UCS of rocks using X-ray computed tomography and convolutional neural networks. First, X-ray CT scanning was conducted on five mudstone specimens. The volume data characteristics of the different density …

Rock Strength - an overview | ScienceDirect Topics

Rock strength is specified in terms of tensile strength, compressive strength, shear strength, and impact strength. In the context of fracture gradient, only the tensile strength of rock is of importance. The tensile strength of rock is defined as the pulling force, required to rupture a rock sample, divided by the sample’s cross-sectional area.


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 classification, the use of the well -known point load strength index can be useful as the


THE UNIAXIAL COMPRESSIVE STRENGTH OF SOFT ROCK D. S. Agustawijaya Lecturer, Department of Civil Engineering, Faculty of Engineering, Mataram University, Mataram, Indonesia Email: [email protected] ABSTRACT Soft rock is a term that usually refers to a rock material with a uniaxial compressive strength (UCS) less than 20 MPa.

Predicting Unconfined Compressive Strength of Intact

Intact rock Unconfined compressive strength specimens. However, preparing fresh cores is not always possible, especially during the Adaptive neuro-fuzzy inference system Genetic algorithm Particle swarm optimization. Abstract Bedrock unconfined compressive strength …

Bearing Capacity of Rocks

In case of rock mass with favorable discontinuities, the net allowable bearing pressure may be estimated from: q a = q c * N j Where qWhere q c = average uniaxial compressive strength of rock coresaverage uniaxial compressive strength of rock cores N j = empirical coefficient depending on the spacing of the discontinuities 3+S/B 10 []1+300(δ/S) δ= thickness of discontinuity= thickness of .

Bearing Capacity of Rocks | Civil Engineering

The bearing capacity of a homogeneous, and discontinuous rock mass cannot be less than the unconfined compressive strength of the rock mass around the footing and this can be taken as a lower bound for a rock mass with constant angle of internal friction 0 and unconfined compressive strength qur. Goodman (1980) suggests the following equation .

(PDF) Strength Classification of Rock Material Based on

 · Intact rock materials are generally classified with regard to the strength, such as uniaxial compressive and point load strength. Rock texture, which consists of grains and matrix, directly .


Peabody established an in house rock mechanics testing facility in the fall of 1986. This facility is located in Freeburg, IL. A full range of equipment was purchased to perform tests including uniaxial compressive strength, indirect tensile strength, point load index, triaxial compressive strength, flexural

ASTM D7012 - 14e1 Standard Test Methods for Compressive

5.2 Method C, uniaxial compressive strength of rock is used in many design formulas and is sometimes used as an index property to select the appropriate excavation technique. Deformation and strength of rock are known to be functions of confining pressure. Method A, triaxial compression test, is commonly used to simulate the stress conditions under which most underground rock masses exist.

Empirical Estimation of Uniaxial Compressive Strength of

 · The uniaxial compressive strength (UCS) is a mechanical property of intact rocks that is important in civil and mining engineering works (Aladejare 2020; Aladejare et al. 2020; Wang and Aladejare 2016a).Design and stability analysis of underground excavations and other geotechnical structures require the input of data like UCS on the geomechanical behaviour of rocks (Ulusay et al. …

Experimental investigation on strength and failure

The strength of rock is many times higher than that of the CPB-R composite. The uniaxial compressive strength of the CPB-R composite is related to the O-t ratio and the interface angle. Table 2. Uniaxial compressive strength of specimens. Specimens type interface angle (°)