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From page 206... ... 206 C H A P T E R 1 0 Evaluation of Rock Mass Properties Introduction The engineering behavior of rock masses under loading depends upon the assemblage of composite components, including (i) intact rock material and (ii) Read the entire page →
From page 207... ... 207 Source: William Menke Figure 10-1. Diversity of rock types found in the conterminous United States. Read the entire page →
From page 208... ... 208 Grain Aspects Sedimentary Metamorphic Igneous Clastic Carbonate Foliated Nonfoliated Intrusive Extrusive Medium Sandstone (19) Siltstone (9) Read the entire page →
From page 209... ... 209 Source: Paul Mayne Figure 10-2. Geologic time scale and associated age of rocks Intact Rock Properties Intact rock material can be quantified in terms of density, strength, stiffness, and other properties, as discussed in this section. Read the entire page →
From page 210... ... 210 Source: Paul Mayne Figure 10-3. Specific gravity of solids of common rock minerals 10.3.2 Unit Weight The unit weight of rock depends upon its porosity (n) Read the entire page →
From page 211... ... 211 Source: Paul Mayne Figure 10-4. Unit weight of saturated rock vs. Read the entire page →
From page 212... ... 212 Source: Paul Mayne Figure 10-5. Trend for rock unit weight with in situ shear wave velocity It is also possible to estimate the unit weight of rock from compression wave velocity. Read the entire page →
From page 213... ... 213 Source: data from Mayne et al. Read the entire page →
From page 214... ... 214 Source: Paul Mayne Figure 10-7. Measured stress-strain response on intact gneissic rock A selection of measured properties on a varied assortment of intact rocks is listed in Table 10-2, including uniaxial compressive strength, elastic modulus, tensile strength, and Poisson's ratio, as well as their respective sources of data. Read the entire page →
From page 215... ... 215 Rock Type Intact Rock Material Reference Source σu = qu (atm) Read the entire page →
From page 216... ... 216 10.3.6 Poisson's Ratio The Poisson's ratio ( ) is a necessary material input into elasticity solutions for various problems encountered in rock mechanics (Poulos and Davis 1974) Read the entire page →
From page 217... ... 217 10.3.8 Shear Strength of Intact Rock The shear strength is most commonly expressed in terms of the Mohr-Coulomb criterion that is a linear approximation to the strength envelope: = + ∙ where = maximum shear stress (= shear strength) = effective cohesion intercept = effective normal stress = effective stress friction angle The interrelationships between shear strength, uniaxial compressive strength, tensile strength, and general triaxial mode of shearing are depicted in Figure 10-9. Read the entire page →
From page 218... ... 218 parameters. This will be required on large highway projects with appreciable levels of overburden stress such as large slopes and deep tunnels. Read the entire page →
From page 219... ... 219 Table 10-4. Selected guideline values of residual friction angles for rock Type of Rock Friction Angle, (degrees) Read the entire page →
From page 220... ... 220 = 5⁄ ≤ 20 where RQD is expressed in percent (%) Read the entire page →
From page 221... ... 221 Source: based on Bieniawski (1989, 2011) Figure 10-10. Read the entire page →
From page 222... ... 222 Source: modified from Lowson and Bieniawski (2013) Figure 10-11. Read the entire page →
From page 223... ... 223 Additional details may be found in Bieniawski (2011) and Lowson and Bieniawski (2013) Read the entire page →
From page 224... ... 224 Source: after Barton et al. Read the entire page →
From page 225... ... 225 Source: after Hoek (2007) Figure 10-14. Read the entire page →
From page 226... ... 226 Using measurements of shear wave velocity ( ) obtained by suspension logging, Cha et al. Read the entire page →
From page 227... ... 227 3. geological strength index of the rock mass, GSI 4. Read the entire page →
From page 228... ... 228 The rock mass terms s and a are obtained from: = exp − 1009 − 3 = 12 + 16 exp − 15 − exp − 203 Finally, the disturbance factor D depends upon the means of care and quality of the rock extraction, ranging from 0 for undisturbed rock to 1 for completely damaged rock. Table 10-8 provides guidance on the value of D for certain cases: Table 10-8. Read the entire page →
From page 229... ... 229 assumed values of . The latter values are taken at the corresponding overburden stresses for selected depths in the rock formation. Read the entire page →
From page 230... ... 230 Source: Paul Mayne Figure 10-17. Example rock mass strength of fractured marble from Hoek-Brown model to determine c' and φ' using (a) Read the entire page →
From page 232... ... 232 Source: after Peck et al. Read the entire page →
From page 233... ... 233 Source: after Zhang and Einstein (1998) Figure 10-20. Read the entire page →
From page 234... ... 234 Source: after Kulhawy and Phoon (1993) Figure 10-21. Read the entire page →
From page 235... ... 235 studies regarding disintegration rates, deterioration, and break-down of the materials, using slaking and abrasion tests, especially shales and mudstones. In addition, certain rocks (e.g., limestones, dolomite, gypsum) Read the entire page →
From page 236... ... 236 Chapter 10 References Arsonnet, G., J-P. Read the entire page →
From page 237... ... 237 Mayne, P.W., B Christopher, R Read the entire page →

From page 206...

... 206 C H A P T E R 1 0 Evaluation of Rock Mass Properties Introduction The engineering behavior of rock masses under loading depends upon the assemblage of composite components, including (i) intact rock material and (ii)