Mine environment

Lecture 7 Mechanical Properties of Rocks
 Rock properties: mass density, porosity, and permeability
 Stress
 Mohr's circle
 Strain
 Elasticity of rocks
 Rock properties: strength
 Engineering classification of intact rocks
 Rock mass properties

, Rock properties:
 Specific gravity: the ratio between the mass and that of equal volume of water
(i.e. the ratio of mass density and water density).

 Unit weight gamma=(specific gravity)x(unit weight of water)
unit weight of water= 62.4 pcf (lbs/ft3)
for most rocks, gamma = 120 to 200 pcf.

 Porosity n measures the relative amount of void space (containing liquids and
or gases).
porosity=(void space)/(total volume)

 Permeability measures the rate at which fluids will flow through a saturated
materials. We will discuss the measurements of permeability later in the lectu
re of Groundwater.