Swelling Behavior of Shales in Cold Regions

Shale has long been recognized for its tendency to absord moisture and swell when water is available. In cold regions, the interaction of moisture with exposed shale strata is complicated due to the phase change from liquid to solid at temperatures below the freezing point of water. In this study, a series of laboratory tests was performed to quantify the influences of moisture susceptibility of rock, the tempering moisture, and temperature on swelling of shale, with a special emphasis on sub-freezing temperatures. The maximum swelling pressures and the maximum swelling strains developed within the shale samples were measured and the influential factors to swelling behavior of shale were quantified. Besides tempering relative humidity, sample temperature, and moisture susceptibility of shale, changes in air temperature are considered to be important in dealing with potential damage of civil constructions built in weak shales in cold regions. This paper presents the laboratory procedures and results. The three influential factors were related to the swelling behavior of shales. Two quadratic models were proposed to predict the maximum swelling pressure and the maximum swelling strain.