Strain tensor

Volumetric strain

Material constants for isotropic materials

Young's modulus

Bulk modulus

Shear Modulus

Poisson's ratio

Typical Young's modulus values

© Lama, R. D., and V. S. Vutukuri. . Monograph. 1978.)

HANDBOOK ON MECHANICAL PROPERTIES OF ROCKS-TESTING TECHNIQUES AND RESULTS. VOLUME 2

Typical Poissons' modulus values

© Lama, R. D., and V. S. Vutukuri. . Monograph. 1978.)

HANDBOOK ON MECHANICAL PROPERTIES OF ROCKS-TESTING TECHNIQUES AND RESULTS. VOLUME 2

Generalized Hooke's law

For isotropic materials

Relationships between constants

Relationships between constants (contd.)

Siesmic wave velocity

Poroelasticity

Poroelasticity Assumptions1. There is an interconnected pore system uniformly saturated with �uid.2. The total volume of the pore system is small compared to the volume of the rock.3. The pore pressure, the total stress acting on the rock externally, and the stresses acting

on the grains are statistically de�ned.

E�ective stressTerzaghi de�nition

"Exact" e�ective stress

is called Biot's coe�cient

Biot's coe�ceint

For sand

For rocks

Biot's coe�cient (cont.)

© Cambridge University Press (Fig. 3.5c, pp. 69)Zoback, Reservoir Geomechanics