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|Title:||High-strain-rate tensile behavior of sedimentary and igneous rocks at low temperatures|
|Authors:||Henry Krumb School of Mines.|
Dutta, Piyush K.
|Keywords:||Cold regions engineering|
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||CRREL report ; 93-16.|
Abstract: The influence of low temperature on the stress-strain behavior, fracture strength, and energy absorption in the dynamic fracturing of a limestone and a granite was determined by experiments conducted with a special low temperature split-Hopkinson pressure bar in the tensile strain rate regime of 80-100 strains s(-1) . The tensile strength was determined by diametral compression of disk samples (Brazilian method) at -40°C and 24°C. Diametral strains to failure were monitored with a high-speed digital oscilloscope to observe deformations at microsecond intervals. These data were then compared with the results from room and low temperature quasi-static tests. Results show that the tensile strength and the deformability of these rocks are more sensitive to loading rate than to temperature. The mechanism of failure under dynamic loading by stress waves is significantly different from that under quasistatic loading. Dynamic loading produces multiple fractures, absorbs more energy and, because of the cushion of broken rocks produced under the loading surface, requires higher loads for complete failure. The influence of low temperature on strength and deformability under both static and dynamic loadings is less dramatic. Nevertheless, in all cases the strength increased with decreasing temperatures, possibly because of the immobilization of the interfacial water below the freezing temperature.
|Appears in Collections:||CRREL Report|