Experimental research on the development of residual strain in seasonal frozen soil under freezing-thawing and impact type traffic loads

Vehicle load is among the main factors affecting the deformation of subgrade soil. In this research study, the concept of impact type traffic load is introduced to investigate the effects of vehicle load based on the dynamic stress and displacement time histories acquired from seasonal frozen subgrade soils. Using freezing-thawing and dynamic triaxial tests and considering the amplitude and loading sequence of impact type traffic load, the residual deformation characteristics of subgrade soil under impact type traffic loads and freezing-thawing cycles is studied. It was found that under impact type traffic load, the residual deformation of soils increased sharply as the amplitude of impact type traffic load increased. It was also found that the increase in the amplitude of impact type traffic load led to the increase of residual deformation in a scale of power and exponential function. The amplitudes of impact type traffic load affect the development stress-strain path of the residual strain. After the soil experienced the proper amount of pre-vibration of the light load, residual deformation decreased by 15%. After freezing-thawing, the residual strain of soil increased as the amplitude of the impact type traffic loads increased. Also, when the amplification effect of freezing-thawing on the residual strain was basically stable, the residual deformation increased by about 10%. The peak impact type traffic load had a large effect on soil deformation after the freezing-thawing process, leading to the observation that of the earlier the peaks, the stronger the effect of freezing-thawing. After the soil was subjected to preloading with a small load, the influence of the freezing-thawing cycles gradually stabilized. The results may be useful in preventing and controlling the risk of subgrade soil failure when construction takes place spring thaw periods.