Engineering Properties of Jointed Rock
The following set of lecture notes is composed of excerpts of previous papers on the given subject, with specific comments added.
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* All figures quoted in the text are at the end of the lecture. L. Müller (ed.), Rock Mechanics © Springer-Verlag Wien 1972
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K. W. John
Introduction The following set of lecture notes is composed of excerpts of previous papers on the given subject, with specific comments added. The geologic factor of greatest significance in rock mechanics and rock engineering is considered to be the geologic structure represented by joints, faults, and other planes of weakness. This geologic structure differentiates between the rock element and the rock system composed of these elements. If rock mechanics is to achieve real significance in engineering practice, it has to provide methods of analysis which are realistic compromises between the best representation of the actual conditions and pragmatic engineering. The rock mechanics practitioner has to face the fact that many geological engineering and rock mechanics problems may be too complex to allow rigorous analysis but at the same time are deemed satisfactory for construction of major structures. Ultimately, the geotechnical engineer or the engineering geologist has to express the effect of geologic factors in quantitative, even if approximate, terms and provide numerical data on strength and deform ability of rock systems to be utilized in construction. Qualitative evaluations, quantitative descriptions of geologic features as such, and comparisons of specific test results are always of interest but may not suffice as basis for engineering decisions and designs. In the following, concepts are given to quantitatively evaluate the effect of simplified geologic structures. In the present approach, it is proposed to express the properties of a rock system in terms of the parameters of both rock elements and the geologic structure. At this point, reference is made to a most crucial point of any engineering analysis covering geologic materials, the realistic but still manageable idealization of natural conditions, which is to be the input for any analytical attempts. This problem is practically the same for simple and sophisticated methods of analysis of model approaches. Idealization and results based on it always need to be viewed simultaneously in deriving conclusions and recommendations. It is believed, therefore, at the very basic approach given here is justified for engineering purposes in spite of the availability of sophisticated, computer-based methods of analysis. Engineering problem The following specific engineering aspects are to be covered in this approach, with the respective parameters to be assessed quantitatively
Engineering Properties of Jointed Rock
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Strength of regularly jointed rock which is subject to sliding apart upon compression 1.1 Two-dimensional problem as generally considered in engineering studies 1.2 Three-dimensional problems as generally posed due to spatial aspects of the geologic structure 2. Deformability of regularly jointed rock due to sliding apart The analytical approach presented here was derived from the results of biaxia
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