Author(s): L. J. Weber; W. A. Nixon
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Abstract: Ice reinforced with alluvium may be an economic and effective construction material for certain projects in Arctic locations. The variation of strength with respect to soil type must be determined before this material can be effectively uSed. A series of three point bend tests on four soil types show a clear decrease in strength with an increase in mean particle diameter. The four particle types used were a silica sand, a poorly graded quartz sand, a clayey silt, and a well rounded gravel. Testing was performed on beams 80 x 80 x 410mm in dimension, which were approximately 80% alluvium by weight (as close to fully dense as possible). Tests were performed with a Tinnius Olsen Screw driven testing machine, situated in a cold room. All testing took place at a temperature of -5C, and samples were allowed to equilibrate to the test temperature for at least 48 hours prior to testing. The loading rate (i. e. the rate of deflection of the central loading point) was kept constant at 50 mm per minute. The decrease in strength with an increase in particle size may be understood by utilizing a Weibull analysis and considering the micromechanical behavior within the alluvium reinforced ice beam. The Weibull analysis is appropriate because all samples failed in a brittle manner. The effect of soil size is apparently a function of the available space between soil particles. Failure is by cracks forming within the interstitial ice, and the maximum crack which can initiate is limited by the available interstitial volume. This volume is in turn determined by soil size. A simple model illustrates this mechanism and gives good agreement with the observed behavior, though other factors, such as the role of unfrozen water content, must also be taken into account.
Year: 1990