Most soil testing is either of an inferential nature or an environmental nature. The inferential tests investigate empirical properties of the soil in the belief that correlations of empirical parameters with field performance can be extrapolated to embrace simple general laws. Such broad correlations have proven to be inaccurate and extremely limited in use. The environmental tests, in their simplest application, are designed to be of direct use in the determination of specific design criteria for specific problems. This type of testing is highly restrictive and comprises highly specialized specific purpose tests.
In order to avoid the fundamental deficiencies of two testing methods referred to above, a basic postulation of stress-strain-time behavior must be made. With a given behavior postulation, the soil tests take on two purposes. The first purpose is to confirm the stress-strain-time laws previously proposed and then to ascertain numerical values for the controlling soil properties. At this stage the applications are completely general. It still remains that specific soils be tested for specific properties.
This paper is directed towards establishing an analytical basis for setting up certain stress-strain-time laws for soil materials. Based on the conditions of visco-elastic stress-strain-time properties, the test behavior is analyzed for hydrostatic compression, torsion, and for viscometer tests. In addition the unconfined and triaxial test stress-strain-time laws are postulated for various types of visco-elasticity and test conditions.