shear strength

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shear strength The internal resistance of a material to shear stress; this varies depending on temperature, confining pressure, shape, size, loading rate, and amount of pore fluid present. It is measured as the maximum shear stress on an original cross-sectional area that can be sustained. In soils, it is the maximum resistance of a soil to shearing forces under specified conditions. The peak shear strength is the highest stress sustainable just prior to complete failure of a sample under load; after this, stress cannot be maintained and major strains usually occur by displacement along failure surfaces. The residual shear strength is the ultimate strength along a surface or parting in soil or rock after shearing has occurred. For material not previously sheared there is a rapid decline in strength with increasing shear until the residual shear strength is reached.