Experimental study of the dynamic properties of cement- and lime-modified clay soils subjected to freeze–thaw cycles

Modified soils have been used in the recent construction of high-speed railways in northern China due to the lack of good fill material. But the behavior of these modified soils under increased dynamic loading of high-speed train traffic and their long-term performance based on the effects of freeze–thaw cycles have rarely been studied. In this paper, dynamic triaxial tests were conducted on cement- and lime-modified soils with different blend ratios. These soils were subjected to freeze–thaw cycles, and the threshold deviator stress and resilient modulus were studied. The results show that after repeated freeze–thaw cycles, the modified soils exhibit better performance than before modification, the cement-modified clay is superior to the lime-modified clay, and all of the soils' mechanical properties are visibly improved. Moreover, an optimal blend ratio was determined. Also, a critical deviator stress attenuation coefficient, ηf, is introduced to determine the optimal modification method and the appropriate mixture proportions to be used when soils are subjected to freeze–thaw conditions.