Living Reference Work Entry

Encyclopedia of Engineering Geology

Part of the series Encyclopedia of Earth Sciences Series pp 1-2

Date: Latest Version

Deviatoric Stress


Deviatoric stress is the difference between the stress tensor σ and hydrostatic pressure tensor p acting on the rock or soil mass.


Stress that causes a change in volume of a rock or soil reference cube without also causing a change in shape is called hydrostatic pressure, because it acts equally in all directions; thus, hydrostatic pressure is a normal stress. Stress produced by tectonic forces, external loads, and excavations that may remove earth materials which provide support for adjacent earth material differs from the hydrostatic stress and can cause deformations and changes in shape. The reference cube under purely hydrostatic stress conditions need not be rotated to an orientation in which the shear stresses reduce in magnitude to zero and the normal stresses become principal stresses because the hydrostatic pressure tensor consists of only normal stresses. Thus, the hydrostatic pressure p can be subtracted from the normal stresses in t ...

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