Experimental study on mechanical properties of subgrade soil in cold region under different conditions

Abstract

In order to study the change of mechanical properties of subgrade under the condition of thawing after the highway in cold region is subjected to freeze-thaw action all the year round. In this paper, the effects of freeze-thaw cycles, freezing temperature, water content and confining pressure on the mechanical properties of subgrade soil in cold regions after thawing were studied by carrying out indoor mechanical tests, and the mechanical properties of subgrade soil in cold regions after thawing under different conditions were measured. The test results show that : 1 ) after 7 freeze-thaw cycles, the failure stress of subgrade soil decreases from 321.7 kPa to 289.9 kPa, with a decrease of 9.9%, and the elastic modulus decreases by 19.9%. 2 ) When the freezing temperature is reduced from − 5°C to − 15°C, the failure stress of subgrade soil is reduced from 303.9 kPa to 290.1 kPa, which is reduced by 13.8 kPa. The reduction range is about 4.5%, and the elastic modulus is about 1.6%;3 ) When the water content increased from 6–12%, the failure stress decreased from 405.43 kPa to 288.4 kPa, with a decrease of 29.1%, and the elastic modulus decreased approximately linearly, with a decrease of 50.4%. 4 ) When the confining pressure increases from 50 kPa to 150 kPa, the failure stress increases from 194.7 kPa to 367.7 kPa, and the failure stress increases by 88.8%. The elastic modulus increases by 154.1% with the increase of confining pressure. The research results can provide reference for highway and engineering construction in the western silty sand distribution area.