EXPERIMENTAL STUDY ON DYNAMIC STRENGTH OF LIME CLAY SUBGRADE FILLING OF HARBIN-DALIAN PASSENGER DEDICATED LINE

摘要

Based on the dynamic triaxial test data of clay soil and lime clay with 6% mixing ratio of embankment fills of Harbin-Dalian Passenger Dedicated Line, the dynamic strengths and the cumulative plastic strain of clay soil and lime clay subjected to freezing and thawing are studied respectively. The test results show that the critical dynamic stresses of clay soil and lime clay decrease gradually with increasing cycle of freezing and thawing, however, after 6 cycles the critical dynamic stresses have little change. After 10 cycles of freeze-thaw, the critical dynamic stress of clay soil is about 50kPa and the critical dynamic stress of lime clay is about 160kPa. Therefore, the lime clay with 6% mixing ratio may meet the strength request of subgrade fills of high speed railway in seasonal frozen soil regions but the clay soil may not. After varying freeze-thaw circles, the cumulative plastic strain, εp, of lime clay is smaller than of clay soil with the same dynamic load and the addition of lime to clay soil may improve the freeze-thaw durability of clay soil. At last, the prediction model of critical dynamic stress of clay soil and lime clay after freezing and thawing cycles is given and the critical dynamic stresses show an exponential relationship with the number of freeze-thaw circles.