[1][2][3][4][5][6] The shear strength of a discontinuity is often considerably lower than the shear strength of the blocks of intact material in between the discontinuities, and therefore influences, for example, tunnel, foundation, or slope engineering, but also the stability of natural slopes.
The deformation characteristics of a soil or rock mass are also influenced by the shear strength of the discontinuities.
Furthermore, the shear strength of discontinuities influences the stress distribution in a soil or rock mass.
Only for simple models of discontinuities the shear strength can be analytically calculated.
Testing on various scales in the laboratory or in the field, or empirical calculations based on characterizing the discontinuity[12][14][15] are used to establish the shear strength.