Uniaxial compressive strength of intact rock sci = 100 MPa Geological Strength Index GSI = 40 Constant mi = 10 Using the program RocLab1, the uniaxial compressive strength of the rock mass is calculated as sc = 3.307 MPa and the failure envelope for this rock mass is plotted in Figure 1.

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

Compressive strength is measured on materials, components and structures. By definition, the ultimate compressive strength of a material is that value of uniaxial compressive stress reached when the material fails completely. Measurements of compressive strength are affected by the specific test methods and conditions of measurement.

c unconﬁned compressive strength of the weak rock or IGM αfactor of adhesion using the empirical data from ﬁeld tests (Figure 1) Figure 1: Relationship between unconﬁned compressive strength of rock and factor of adhesion (Wyllie, 1999 after Williams and Pells, 1981, courtesy of Research Journals. National Research Council Canada).

The five physical properties and compressive strength vary in quality from dental stone, having superior, to technical plaster with medium quality, ending with local juss with poor or low properties. To avoid repetition of references, these are only stated throughout the discussion regarding the relationships between these properties.

Rock mass strength at depth and impliions for pillar design P. K. Kaiser*1, wall rock behaviour as well as the ultimate load bearing capacity of confined rock, and thus on a compressive strength of the intact rock m b, s and a are functions of GSI (with GSI ranging from 100 for massive

Gneiss, Metamorphic rock, resembling granite in appearance. The grains in gneiss have grown into a parallel structure its compressive strength is higher perpendicular to the grain axes than parallel to this axis. Property values are typical of

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.

The corresponding flow stress was 15 MPa and the ultimate compressive strength (UCS) was 18.34 MPa. Eliminating the time term of the specimen stress and strain histories, the dynamic compressive stressstrain curve is obtained at the strain rate of 48 s −1 and is shown in Fig. 7. Following the same experimental and data processing procedures

strength estimating to intact rock materials as well as jointed rock masses. In this study, the end bearing behavior of a pile embedded in rock was theoretically analyzed based on the slip line principle with considering rock mass damage, and the generalized nonlinear unified strength criterion was used as the constitutive model for bedrock.

Published in: Journal of Central South University of Technology · 2011Authors: Min Zhang · Xinghua Wang · You WangAffiliation: Central South UniversityAbout: Bearing capacity · Geological Strength Index · Differential equation · Computer simulaCompressive Strength of rock: The RMR value depends up on the unconfined compressive strength (q u ) of the rock and it can be determined from laboratory compression test on a prepared rock specimen. Or otherwise find out the approximate value of compression strength from point load test on intact pieces of drill core.

Compressive strength can be defined as the ability of the soil or rock to resist forces imposed on it or the maximum stress that a sample can withstand under specified loading conditions. Trenchless installation projects are carried out in differing soil or ground conditions such as soft soil, medium to hard rock and very hard rock.

Hoek and Brown compiled extensive data on a variety of rock types and produced relationships that are simple and can be developed into forms amenable to welllog analysis. A primary feature of this failure criterion is a relation between the maximum and minimum stresses when both are normalized by the uniaxial compressive strength

The "unconfined" compressive strength is equal to 2 times the undrained shear strength. For all intents and purposes the ultimate bearing capacity is 6 times the undrained shear strength (where c in cNc is the undrained shear strength) or 3 times the unconfined compressive strength.

Compressive Strength of rock: The RMR value depends up on the unconfined compressive strength (q u ) of the rock and it can be determined from laboratory compression test on a prepared rock specimen. Or otherwise find out the approximate value of compression strength from point load test on intact pieces of drill core.

Unconfined compressive strength (UCS) of rocks is a crucial parameter in designing geotechnical structures. Owing to difficulties in obtaining proper samples for UCS test as well as the point that conducting UCS is relatively expensive, the use of indirect methods for UCS estimation has drawn considerable attentions.

Empirical relations between rock strength and physical In this study, 31 empirical equations are summarized that relate unconfined compressive strength and internal friction angle of sedimentary rocks (sandstone, shale, and limestone and dolomite) to physical properties (such as velocity, modulus, and porosity). rock strength to

1.1 These four test methods cover the determination of the strength of intact rock core specimens in uniaxial and triaxial compression. Methods A and B determine the triaxial compressive strength at different pressures and Methods C and D determine the unconfined, uniaxial strength.

Regression Equations for Other Parameters The regression equations for parameters other than the ultimate compressive stress and ultimate axial strain can also be modeled with just two coefficients of regression, one for the inverse of slenderness ratio and the other for the ratio between FRP confining pressure and the unconfined compressive strength of concrete.

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