关键词: 道路工程, 石灰改良土, 路基填料, 冻融循环, 动三轴试验, 动力特性

Abstract: The dynamic characteristics of lime modified soil under freezing and thawing cycles were studied by dynamic tri-axial compression，and the effect of dynamic stress amplitude，freeze-thaw cycles，cooling temperature and confining pressure on the cumulative plastic deformation of the soil was analyzed.The prediction model of cumulative plastic deformation was established under dynamic stress and freezing-thawing cycles.Based on the analysis of cumulative plastic deformation，the effect of the ratio of cement and the number of freezing and thawing cycles on the critical dynamic stress was further analyzed.And then the conclusion that the critical dynamic stress of the clean soil was less than 80 kPa and the critical dynamic stress of lime modified soil was between 150 kPa and 250 kPa was drawn.On the basis of the standard value of dynamic resilient modulus of subgrade MR in standard condition，the subgrade soil modulus reduction coefficient Kηunder the freezing-thawing cycle and the humidity adjustment coefficient of resilient modulus of subgrade KS were introduced.Therefore，the dynamic resilient modulus of subgrade was obtained under the influence of freezing-thawing cycle and subgrade soil moisture.The resilient modulus of lime modified soil on the top and bottom surfaces of subgrade work area was 70.18 MPa and 58.48 MPa respectively，which can meet the requirements of resilient modulus of subgrade.

Key words: highway engineering, lime modified soil, subgrade filling, freezing and thawing cycle, dynamic tri-axial compression test, dynamic characteristics