Effects of sodium sulfate content on mechanical behavior of frozen silty sand considering concentration of saline solution

摘要

Highlights ? Mechanical properties of a frozen saline silty sand were investigated. ? Confining pressure and sodium sulfate content were varied in the study. ? Concentration of sodium sulfate solution was related to sodium sulfate content. ? A method was proposed to identify the saturated/unsaturated state of frozen soil. ? Strength of frozen saline silty sand increases with higher sodium sulfate content. Abstract Triaxial compressive tests were conducted on a frozen silty sand with four sodium sulfate contents (0.0%, 0.5%, 1.5%, and 2.5%) at temperature of ?6 °C. The test results revealed that it is important and necessary to firstly identify whether the concentration of sodium sulfate solution in the silty sand is saturated for studying effects of the salt content on the strength and deformation characteristics. We established a function which can interconvert the concentration of the sodium sulfate solution and the sodium sulfate content in the silty sand if either one of these two variables is a known quantity. Based on this function, the saturated or unsaturated state of the concentration of sodium sulfate solution corresponding to each given sodium sulfate content in the frozen silty sand can be conveniently identified. The influence of confining pressure and sodium sulfate content on the deformation characteristics, failure mode and strength of the frozen saline silty sand were then analyzed.