Regarding the anelastic volume variation (overall minus elastic volume change), at all three temperatures it remains very close to zero and then at a strain near to the maximum stress a major change in the volume strain
curves slope occurs.
And the volume strain
[[epsilon].sub.v] and crack volume strain
[[epsilon].sub.cv]  under triaxial compression can be written by
Meimon, "Volume strain
changes of plasticized poly(vinylidene fluoride) during tensile and creep tests," Journal of Applied Polymer Science, vol.
 established the function relationship between rock mass porosity and isotropic volume strain
. Then, the quantitative relationship between rock mass deformation and permeability was determined, and the numerical analysis of a fluid-solid coupling process in a deep rock mass project was realized.
For example, during the beginning stage of a constant-strain-rate tension, the volume strain
shows a small reduction, which is beyond understanding because on the base of the classical mechanics there could be not the reduction of volume strain
in stretching process.
Together with the phases, the signs of the co-seismic amplitude change as well as the co-seismic and post-seismic patterns of volumetric strain and water level, we obtain the coupling mechanism of the volume strain
change and the water level change: Before the earthquake, tidal volumetric strain induced the change of water level (the phase of the water level lagged behind that of the volume strain
In the case of uniaxial tension, the plastic Poisson ratio [nu] is defined as Equation (3), and the relationship between plastic Poisson ratio [nu] and volume strain
[theta] is presented as Equation (4).
Under hydrostatic compression, the bulk modulus (B) is defined as the ratio, hydrostatic pressure to volume strain
Under the assumption of transversal isotropy, the lateral contraction is the same in the two transversal directions, therefore it is possible to evaluate the volume strain
, [DELTA]V/[V.sub.0], as
The differences of volume strain
corresponding to the same axial strain are up to 8%.
Meanwhile, pressure is a function of volume strain
, and damage accumulation is a function of plastic volume strain
, equivalent plastic strain, and pressure.
Based on the observation of both water levels and volume strains
in the Fuxin well, northeastern China, the 2011 Mw 9.0 Tohoku earthquake produced huge-energy teleseismic waves, leading to an extreme decrease of volume strain
and an abrupt increase of water level in the aquifer at far fields (epicentral distance >1800 km).