Strength properties of ice-rich frozen silty sands under uniaxial compression for a wide range of strain rates and moisture contents

With the increase in engineering construction in ice-rich permafrost regions, the strength characteristics of ice rich frozen soils have attracted the attention of researchers and engineers. However, few laboratory data address the uniaxial compressive strength of frozen soils for a wide range of strain rates and moisture contents. In the present study, a series of uniaxial compressive tests were conducted on ice-rich frozen silty sands using temperature conditions of -0.5, -1.0, -2.0, and -5.0 degrees C, moisture contents of 16.7-1480.0%, and strain rates of 1.07 x 10(-5) to 1.13 x 10(-2) s(-1). The results show that brittle failure occurs easily in the ice-rich frozen silty sands, except for those with a moisture content of approximately 31.0%. When the moisture content is low, the strength increases nonlinearly with increasing strain rate. However, when the moisture content is high, a peak strength appears on the strength-strain rate curve. For strain rates less than 5.33 x 10(-4) s(-1), as the moisture content increases, the strength first decreases from a maximum value at optimum dry density to a minimum value that is less than the ice strength. The strength then increases to the ice strength. For strain rates greater than 2.00 x 10(-3) s(-1), as the moisture content increases, the strength first decreases to a minimum value, then increases to a maximum value, and finally decreases toward that the ice strength; the minimum strengths are not always less than the ice strength, and the maximum strengths are not also always greater than the strengths at the optimum dry densities. (C) 2015 Elsevier B.V. All rights reserved.