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  • Lecture 9Introduction to Rock Strength David Hart

     · UNIAXIAL COMPRESSIVE STRENGTH C o (x 1000 psi) 0 50 100 150 SPECIMEN LENGTH L (in.) VARIATION OF COMPRESSIVE STRENGTH WITH SIZE C o = 35 x L-0.14 In this plot of the size effect on strength a power function was used to best-fit the experimental data. NOTE however that beyond L=36 in. the size effect ceases to be of much consequence.

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  • Estimating Rock Mass StrengthBM 1997 02

     · The Hoek-Brown strength criterion was applied to estimate the strength of the rock mass at the Aznalcollar open pit. It was shown that by assuming disturbed rock mass a good agreement was found between estimated strength values and back-calculated strengths from observed slope failures in the footwall. These values are probably conservative and

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  • JJMIE Volume 12 Number 2 September. 2018 ISSN 1995

     · compressive strength. There is a linear relationship between the coal strength and cutting force. However the cutting force fluctuation which is coefficient of different coal and rock strength did not show the same distribution. 3.2. The influence of pick-tip cone angle on the cutting force

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  • Prediction of Rock Strength using Drilling Data and Sonic

     · Unconfined Compressive Strength Log (UCSL) is a representation of the apparent rock strength in a particular well or section derived from the actual historical drilling data. To calculate the rock strength with the ROP models as described above drilling data

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  • COMPARING THE RMR Q AND RMi CLASSIFICATION

     · than between Q and RMR. A main reason for this is that Q does not use input of the compressive strength of intact rock. It further shows that weakness zones are poorly covered by the commonly used correlation equation (see Figure 1 in Part 1) between Q and RMR.

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  • Piles CapacityReference ManualhetGE

     · The tip resistance of a pile socketed in weak rock or IGMs can be approximated with the following formula which uses a wide range of field test data (Figure 2). q b=4.83⋅(σ c) 0.51 (13) Figure 2 Relationship between compressive strength of weak rock and end bearing capacity (Zhang 2004 after Zhang and Einstein 1998) Piles Capacity

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  • Statistical Variations and New Correlation Models to

     · Effects of rock classes and porosity on the relation between uniaxial compressive strength and some rock properties for carbonate rocks. Rock mechanics and rock engineering 45(1) . Search in Google Scholar 39 Richard T. Dagrain F. Poyol E. and Detournay E. (2012). Rock strength determination from scratch tests.

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  • The Hoek–Brown Failure Criterion

     · estimate rock mass strength by scaling the relationship derived according to the geological conditions present. The criterion was conceived based on Hoek s (1968) experi-ences with brittle rock failure and his use of a parabolic Mohr envelope derived from Griffith s crack theory (Griffith 1920 1924) to define the relationship between

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  • Correlation of rock strength between uniaxial compressive

     · Rock engineering design for underground or on-the-ground projects and operations are widely dependent on different properties of rocks among which strength is one of the main components. The uniaxial compressive strength (UCS) test is still considered to be the most effective method currently used by many industries to estimate either intact or rock mass nbspstrength along with other rock

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  • 8. STRENGTH OF SOILS AND ROCKS

     · material is compressed between the platens of a testing machine as illustrated in Fig. 8.1. The compressive strength is then defined as the maximum load applied to crush the specimen divided by the cross-sectional area. Rock strength has been found to be size dependent because of the cracks and fissures that are often present in the material.

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  • Comparative Study of the Abrasion Resistance

     · rock (CTR) limestone (LS) and river rock or pea gravel (PG). Proportioning of all mixes was done following the American Concrete Institute Standard Practice. Comparison of all mixes based on testing of their compressive strength abrasion coefficient and

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  • Correlation between Uniaxial Compressive Strength and

     · uniaxial compressive strength from the results of the point load test. 4. Test Results and Discussion 4.1 Uniaxial Compressive Strength Test Results The mean values of uniaxial compressive strength of the tested rocks are listed in Table 2. The strength values range from a low of 9.16 MPa for Marl to a high of 101.08 MPa for

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  • (DOC) Conversion of Point Load Test Results to

    Also it is concluded The uniaxial compression test (UCS) and that a conversion between 21-24 for harder rocks Indirect Tensile Strength Index (ITS) are two and 14-16 for softer rocks should be used. important rock mechanics tests used to 4 determine compressive strength of rock Mark and Rusnak had used experimental specimens.

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  • What is the relation between stiffness and young s modulus

    1. Determine the stiffness by considering the load vs deflection value within elastic limit i.e. k (stiffness) = f (load)/x (deflection) 2. k = Area of composite specimen x young s modulus

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  • (PDF) CORRELATION BETWEEN UNIAXIAL COMPRESSIVE

    The new multi-linear correlation for determining unconfined compressive strength with the help of point load index is developed and cross checked with equations formed for actual rock.

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  • The effect of rock classes on the relation between

     · Uniaxial compressive strength and point load tests were carried out on 17 igneous 16 metamorphic and 19 sedimentary rocks and the values correlated with their I s values. The influence of the different rock type was investigated using regression analysis and the derived equations were statistically tested. Although the derived equation for all data is significant the data points are

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  • The misuse of SPTs in fine soils and the implications of

     · used in relation to soil type for the "preliminary" design stage only. Limited information is available on correlations between the coefficient of volume compressibility and SPT N value. In addition the correlations all too often refer to unconfined compressive strength (Terzaghi

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  • Evaluation of rock mass strength criteria

     · strength and a better rock mass strength estimation method should be developed. This requires more case histories where the determined/estimated rock mass strength from the criteria/systems can be compared to the measured/determined rock mass strength. Keywords Hard Rock Mass Strength Failure Criterion Classification Characterisation

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  • The Hoek–Brown Failure Criterion

     · estimate rock mass strength by scaling the relationship derived according to the geological conditions present. The criterion was conceived based on Hoek s (1968) experi-ences with brittle rock failure and his use of a parabolic Mohr envelope derived from Griffith s crack theory (Griffith 1920 1924) to define the relationship between

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  • STRENGTH PROPERTIES OF ROCKS AND ROCK MASSES 1

     · between strain hardening and softening is called the unconfined compressive strength of the rock and is denoted as Co or qu. Failure takes place continuously from C to D during which macrocracking takes place as the rock becomes more deteriorated and crack coalescence takes place.

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  • Compressive Strength of Concrete -Cube Test Procedure

     · The compressive strength of the concrete cube test provides an idea about all the characteristics of concrete. By this single test one judge that whether Concreting has been done properly or not. Concrete compressive strength for general construction varies from 15 MPa (2200 psi) to 30 MPa (4400 psi) and higher in commercial and industrial

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  • JME

     · Keywords Coal field Roof rock Schmidt number uniaxial compressive strength. 1. Introduction Rock mechanics engineers design structures built in rock for various purposes and therefore need to determine the properties and behavior of the rock. The UCS of rocks is one of the important input parameters used in rock engineering projects such

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  • Rock mass propertiesRocscience Inc.

     · value of the Geological Strength Index GSI for the rock mass. Intact rock properties For the intact rock pieces that make up the rock mass equation (1) simplifies to 0.5 3 1 3 1 ci ci m i (5) The relationship between the principal stresses at failure for a given rock is defined by two constants the uniaxial compressive strength and a

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  • Statistical Variations and New Correlation Models to

     · Effects of rock classes and porosity on the relation between uniaxial compressive strength and some rock properties for carbonate rocks. Rock mechanics and rock engineering 45(1) . Search in Google Scholar 39 Richard T. Dagrain F. Poyol E. and Detournay E. (2012). Rock strength determination from scratch tests.

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  • 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

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  • 8. STRENGTH OF SOILS AND ROCKS

     · material is compressed between the platens of a testing machine as illustrated in Fig. 8.1. The compressive strength is then defined as the maximum load applied to crush the specimen divided by the cross-sectional area. Rock strength has been found to be size dependent because of the cracks and fissures that are often present in the material.

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  • Vipulanandan p–q model to predict the effect of

     · In this study the effects of soaking time and confining water pressure on the compressive and flexural strengths of rock due to the dissolution of gypsum content in rock samples with 96 gypsum (CaSO 4 ·2H 2 O) content collected from northern Iraq (Kurdistan Region) were investigated. Experiments on compressive strength and flexural strength were performed on gypsum rock samples

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  • Correlation between Pulse Velocity and Compressive

     · grade of concrete were plotted for establishing relation between UPV and compressive strength. The linear regression was applied to establish the UPV-strength relationship. Fig. 2 Fig. 3 and Fig. 4 shows the relationships between UPV and strength at the age of 28 days of concrete having M15 M20 and M35 grades of concrete respectively.

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  • Hoek-Brown failure criterion2002 Edition

     · stress relationships of the original Hoek-Brown criterion defined by the equation 0.5 3 3 1 = m s ci ci s s s s s (1) where 1 s and s 3 are the major and minor effective principal stresses at failure s ci is the uniaxial compressive strength of the intact rock m at i l nd m nd s rem ti l c os wh = 1 f intact rock. A ex ac tr l

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  • Compressive strength of rocksPetroWiki

     · 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

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  • Correlation of rock strength between uniaxial compressive

     · Rock engineering design for underground or on-the-ground projects and operations are widely dependent on different properties of rocks among which strength is one of the main components. The uniaxial compressive strength (UCS) test is still considered to be the most effective method currently used by many industries to estimate either intact or rock mass nbspstrength along with other rock

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  • Utilizing the strength conversion factor in the estimation

     · Many researchers have investigated the relation between UCS and PLI for different rock types using the UCS/PLI ratio which is termed the strength conversion factor (k). Broch and Franklin (1972) indicated that the UCS was approximately 24 times the PLI for a standard-size (50-mm) core.

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