Skip to main content
Geothermal Energy

Science – Society – Technology

Figure 1 | Geothermal Energy

Figure 1

From: The significance of hydrothermal alteration zones for the mechanical behavior of a geothermal reservoir

Figure 1

Friction coefficient and parameter ( a-b ) for different rock types. (a) Friction coefficient for rocks and a soil with different clay contents. Increasing clay content reduces the frictional strength. (b) Range of measured friction coefficients for different rock types (data from Ikari et al. [2011]). (c) (a-b) parameter for rocks and soil with different clay contents and (d) (a-b) for different rock types. With increasing clay content, the friction coefficient is reduced and (a-b) increases. High clay content and low friction result in velocity-strengthening behavior. Rock types with low friction show velocity-strengthening behavior. Experimental data from Zoback et al. ([2012]) is derived from measurements on shale, and Tembe et al. ([2010]) measured artificial quartz-illite samples. Akayuli et al. ([2013]) did experimental studies on soil.

Back to article page