Maximum Principle Stress In Granite

Four types of stresses act on materials.

Maximum principle stress in granite.

On any plane within an object there is a normal stress σ n perpendicular to the plane and shear stress τ acting. In geology stress is the force per unit area that is placed on a rock. This theory states that a structural component will fail when maximum principal stress of the system will become equal to the yield strength of same material in a simple tension test 3 d equations for ductile materials. This is called confining stress.

The surfaces of maximum shear stress are failure surfaces i e. Shearing stress stress that tends to shear the material acts in. σ 1 σ yt. Compressive stress stress that tends to compress or shorten the material acts normal to the stressed area.

Faults that deform by shear strain and they will have an orientation that depends on the magnitude and orientation of the stresses. The mean stress reaches approximately 40 mpa at 1000 m depth. Stress is the ratio of applied force f to a cross section area defined as force per unit area. Maximum principle stress theory or normal stress theory says that yielding occurs at a point in a body when principle stress maximum normal stress in a biaxial system reaches limiting yield value of that material under simple tension test.

Maximum principal stress theory. It is part of plasticity theory that applies best to ductile materials such as some metals. Most recently martin 2007 established the stress gradient model using borehole breakout analysis utilizing principle stress ratio mean principal stress and spalling ratio and suggested the horizontal and vertical in situ stress gradients to the depth of 1000 m given in fig. The maximum distortion criterion also von mises yield criterion considers that yielding of a ductile material begins when the second invariant of deviatoric stress reaches a critical value.

Stress is the force applied to an object. Since the rock cannot move it cannot deform. Tensile stress stress that tends to stretch or lengthen the material acts normal to the stressed area. The uncompressed rigid aperture of a fracture is proportional to its shear displacement.

The induced aperture reaches a maximum at β 60 due to an optimal combination of shear and normal stress which allows for maximum displacement during fracture closure and minimal compression in contact. Prior to yield material response can be assumed to be of a nonlinear elastic viscoelastic or linear elastic. A deeply buried rock is pushed down by the weight of all the material above it.