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Chapter 1
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Chapter 3
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Chapter 6
Chapter 7
Chapter 8
Chapter 9
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Chapter 12

Chapter 8: Elastic Behavior

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In this chapter we describe how the elastic properties of rock are measured in the laboratory and provide tables of representative values for different rock types. However, the need to understand the resistance of rocks to deformation goes well beyond the accumulation of numbers in handbooks. To analyze a geological structure one must choose the appropriate boundary- or initial-value problem to serve as a mechanical model, and one must postulate a particular mechanical behavior. That is, one must say exactly what the relationship is between the stress acting within a material and the strain or rate of deformation. These relationships are called constitutive equations. For example, Hytch et al. (2003), studying the displacement field around an edge dislocation in silicon as revealed by electron microscopy (see above), postulated an anisotropic linear elastic constitutive law and calculated model displacements, ux and uy, that are remarkably similar to those observed in the laboratory experiment.