A RHEOLOGIC INVESTIGATION OF THE DYNAMIC RESPONSE SPECTRA OF SOILS.
Rept. no. 4.
NORTHWESTERN UNIV EVANSTON ILL TECHNOLOGICAL INST
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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
- Soil Mechanics
- Test Facilities, Equipment and Methods