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

- Brittle failure occurs easily in ice-rich frozen silty sands.
- Strength increases nonlinearly with increasing strain rates at low moisture contents.
- For high moisture contents, there is a peak strength on the curve of strength-strain rate.
- The relationship between strength and moisture content depends on the range of the strain rate.

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 °C, moisture contents of 16.7-480.0%, and strain rates of 1.07 × 10− 5 to 1.13 × 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 × 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 × 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.