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Conducted laboratory tests and results
Published in Yan Xing, Pinnaduwa H.S.W. Kulatilake, Louis Sandbak, Rock Mass Stability Around Underground Excavations in a Mine, 2019
Yan Xing, Pinnaduwa H.S.W. Kulatilake, Louis Sandbak
Rock samples were collected by the mining company and sent to the Geomechanics Laboratory at the University of Arizona for testing. Figure 6.1 shows the boreholes (short and straight lines) where the rock cores were taken with respect to the tunnel system. Diverse locations and orientations of the boreholes can be observed. Detailed information about the locations and geometry of these boreholes is given in Table 6.1; the location ranges of the selected study area are provided after the table. The involved rock types include dacite, mudstone and limestone. Geomechanical laboratory tests were carried out, including Brazilian, uniaxial compression, ultrasonic, triaxial, uniaxial joint compression and small-scale direct shear tests. The tests were performed as per the American Society for Testing and Material (ASTM) standards. A detailed description of the sample preparation and the results and analyses of the tests is presented in this chapter.
Soil Mechanics
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
The safety of many engineering endeavors depends on soil strength, because if soil fails, any structures built on or in it will fail too. To evaluate soil strength, engineers must be able to predict the effects of forces acting on a soil and determine whether a soil will support any proposed activities. When a force is applied to a volume of soil, rock, or any other material, the effects depend on how intense the force is. A moderate amount of force applied to a very large surface may cause insignificant effects, but the same amount of force applied to a very small area may cause major deformation. The key consideration is ratio of force to area, called stress: stress = force/area When enough stress is applied to any material, it will deform. The amount of deformation caused by stress is termed strain. Stress, strain, and the relationships between them are important considerations in many geology and engineering subdisciplines, especially geomechanics, a specialized area of engineering involving application of classical mechanics to geological materials.
Autoprogressive algorithm and self-learning simulation
Published in Jamshid Ghaboussi, Soft Computing in Engineering, 2018
Professor Paul Lade performed the first nonuniform material tests on sand (Lade et al., 1994) to be used in autoprogressive training of neural network material models. Most material tests in geomechanics use triaxial test with cylindrical specimens. The specimen is subjected to axial and radial stress. To maintain a uniform state of stresses and deformations, the friction at the top and bottom of the sample is reduced as much as possible, and, if possible, it is eliminated. To generate nonuniform state of stress and deformation, Professor Lade used shorter specimens and increased the friction between the top and bottom of the sample and the end plates in the triaxial tests on sand. The friction at ends of the cylindrical specimen causes bulging around the middle that leads to nonuniform state of deformations. End frictions also cause nonuniform state of stress with shear stresses at the top and bottom of the sample.
Geomechanical characterisation of discontinuous greywacke from the Wellington region based on laboratory testing
Published in New Zealand Journal of Geology and Geophysics, 2022
Marc-André Brideau, Christopher I. Massey, Jonathan M. Carey, Barbara Lyndsell
The geomechanical properties of a rock mass are a fundamental consideration for engineering design e.g. foundations, earthworks, tunnels, bridges, quarrying, excavations and slope stability. Characterising the geomechanical properties of discontinuous rock masses can be difficult as they are influenced by the properties of the intact rock, discontinuities, and structure of the rock mass (e.g. Hoek and Brown 2019; Carter and Marinos 2020). These factors are also influenced by the scale of observation and testing (e.g. Heuze 1980) and by weathering (e.g. Hodder and Hetherington 1991). The Torlesse greywacke rock masses in the Wellington region comprise interbedded mudstone (siltstone and argillite) and sandstone that are dominated by multiple sets of closely-spaced discontinuities (Figure 1A), which vary in persistence and spacing, thus making characterisation challenging (Figure 1B). Based on their rock engineering experience in greywackes of the southern part of the New Zealand North Island, Cammack et al. (2019) presented a rock mass classification system and structural regimes to characterise the range and complexity of structure and weathering grade encountered in the region. This approach builds on previous schemes by Read and Richards (2007) and extends it to include wider ranges of weathering grade and tectonic disturbance.
Geomechanical study of gas reservoir rock using vertical seismic profile and petrophysical data (continental shelf in southern Iran)
Published in Geomechanics and Geoengineering, 2019
Mohammad Abdideh, Mohammad Ali Moghimzadeh
Nowadays, in advanced countries of the world, the use of geomechanics is one of the most influential issues in oil and gas such that it simplifies the evaluation and interpretation of the problems in oil industry. Geomechanics deals with the investigation of rock behaviour affected by the imposed stresses. The aim of geomechanics investigations is to obtain elastic modules (Ameen et al. 2009).