The basic development and operation characteristics of a high speed, explosive, pulse type compression apparatus for the dynamic testing of cohesive soils is presented. Dynamic loading is obtained by firing a Springfield 30-06 cartridge charged with gunpoder into a combustion chamber. The high pressure developed drives a piston and deforms the soil specimen in unconfined compression. Details of the design, construction, and instrumentation of the device are given. In addition, performance characteristics as well as preliminary results of a limited test program are also reported. The range of the time spectrum studied is from approximately 0.1 milli-second to 5 miliseconds. The apparatus is discussed both as a table-top device and for use in conjunction with large static type testing machines. Correlation of acceleration, velocity, displacement, and force measurements are presented and inertial effects are discussed. Test results are given for soil specimens with moisture contents ranging from 24.6 percent to 39.9 percent. Dynamic stress-strain response is represented by a hyperbolic equation and values of initial compliance are compared with the initial compliance-time spectrum developed from the results of creep and steady state vibratory test programs. Total strain and elastic strain spectra are compared and discussed in terms of applicable strains. Blast pulse response is shown to be in excellent agreement with the creep-vibratory total strain response spectra. (Author).

The motivating philosophy for a rheologic study of the dynamic response spectra of soils is pre sented. Basic concepts regarding the method of approach, equipment development, experimental techniques, preparation and control of soil specimens and preliminary results of the soil response under various loading conditions in uniaxial compression are given. Dynamic visco elastic techniques are utilized and the linear and nonlinear aspects of soil response under dynamic and static loading conditions are studied. The variables considered include dynamic stress level, dynamic strain level, strain rate, static stress level, tim of loading, frequency of load application, phase angle, quasi-static strains, strain recovery, moisture content, density, un confined compressive strength and specimen geometry. (Author).

The results of an investigation of the energy storage and energy dissipation properties of a cohesive soil are presented. Major emphasis is directed at energy dissipation as well as phenomena associated with energy dissipation. Soil response is represented in terms of viscoelastic parameters. Both direct and indirect methods of determining energy dissipations are considered. Damping capacity as a function of frequency is determined directly by measuring the phase angle, delta, between applied and resulting waveforms in uniaxial (unconfined) compression with controlled sinusoidal vibration. The results are given in terms of the loss tangent, tan, delta. The loss tangent is dependent on moisture content, frequency, and amplitude of dynamic stress-strain; but specimen geometry and static stress level, within the range considered seem to have no definite effect on the results. The experimental response is definitely nonlinear. Energy dissipation is also obtained by indirect methods through the application of Fourier transformation techniques to experimental data obtained from creep and stress relaxation tests. The loss tangent relations obtained using the Fourier Transforms are comparable to those obtained by the direct stress-strain-phase angle method.