(1. College of Water Conservancy and Hydropower Engineering，Hohai University，Nanjing，Jiangsu 210098，China； 2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering，Hohai University，Nanjing，Jiangsu 210098，China)
Abstract：In order to study the effects of freeze-thaw cycles on the volume changes and mechanical properties of clay-gravel mixtures，the freeze-thaw test was carried out on clay-gravel mixtures，and it was concluded that the sample volume will shrink when frozen，and the sample height shrinkage is less than the diameter shrinkage. When the number of freeze-thaw cycles exceeds 5 times，the sample volume tends to be stable. Besides，a series of unconsolidated and undrained triaxial tests were conducted with the different numbers of freeze-thaw cycles under various confining pressures，and the stress-strain behavior，failure strength，elastic modulus，cohesion and angle of internal friction were analyzed. The testing results show that the mechanical properties of clay-gravel mixtures are affected considerably，but the shape of the stress-strain curve doesn?t be influenced by the freeze-thaw cycles. After the first freeze-thaw cycle，the failure strength of the sample decreased sharply，and when the number of freeze-thaw cycles exceeds 2 times，the failure strength of the sample shows a trend of slowly decreasing first and then increasing slowly as the number of freeze-thaw cycles increases. The elastic modulus under various confining pressures decreases first and then increases with the increase of the number of freeze-thaw cycles，and the samples will get a minimum elastic modulus after 4–6 freeze-thaw cycles. The cohesion decreases first and then increases slowly as the number of freeze-thaw cycles increases，but the angle of internal friction is almost unaffected by freeze-thaw cycles. It is suggested that the strength parameter after 6 freeze-thaw cycles can be used as design parameters for engineering design of clay-gravel mixtures in seasonally frozen regions.
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2021, Vol. 40 
