Dynamic Behavior And Application Of Improved Lime-Soil Of Subgrade After Dry-wet Cycles

With the great development of high-speed railway and heavily loaded railway in modern society, the standard of improved filling materials of subgrade-soil become higher and higher. The improved soil needs to keep excellent dynamic properties because it works under the cyclic load of train. Scholars have already discussed the effect of the change of environment on dynamic behavior of cement-soil, so it is very important to study the dynamic behavior of other kind of improved-soil (lime-soil) and analyse quantitatively the effect of dry-wet process on dynamic behavior of lime-soil. Toward these problems the following works will be carried out.Firstly, the relationship between dry-wet process and the cyclic fatigue strength is studied. We measure the cyclic fatigue strength in multi-situation of dry-wet process through cyclic triaxial tests. Then the effect of the number of dry-wet process on descend of cyclic fatigue strength is derived from analyzing of test results.Secondly, the effect of dry-wet process on the dynamic deformation of lime-soil is studied according to the reality of subgrade-soil. We describe dynamic stress-strain relationship of improved-soil through the elastic modulus E_d,the damping ratioλand the dynamic plastic strainε_p. The effects of cyclic dry-wet process on this dynamic stress-strain relationship are researched.Finally, according to the practical construction,design demand of high-speed railway and test results, the stress on subgrade is analyzed, the method of strength checking- computations for improved soil which experience cyclic dry-wet process is discussed. Then we apply the unilateral layer wise summation method to dynamic deformation calculation of subgrade-soil in super railway, and calculate dynamic deformation of improved filling materials of subgrade-soil under train load through a example.