Experimental determination of viscosity of rocks

An important parameter involved in the viscoelastic deformation of structural materials is the coefficient of “solid” viscosity. Determination of this parameter is necessary, if it is to be used in structural design. This paper deals with pertinent analytical considerations concerning solid viscosity and describes the procedures followed in the determination of parameters for structural and true viscosity of a Queenston limestone. The following three techniques were used:

1. Relaxation technique
2. Uniaxial compressive loading
3. Cantilever-beam loading

The results obtained are in close mutual agreement except for (2) above, where experimental conditions were different from those in (1) and (3). A quasi-periodic behavior of strain is indicated. It has been shown that the solid viscous parameter is a transient property and may depend on such factors as applied load, time, grain size, grain-packing in a material, and the direction of testing. It has been concluded that coefficients of true and structural solid viscosity of materials can be determined for a given set of conditions.