Research on Influence of Overburden and Weathered Sand on Modified Expansive Soil

How to determine the rational soil cover depth of highway expansive soil roadbed is a key problem of expansive soil roadbed design.Expansive force experiment and loaded swelling ratio experiment under different overburden of weathered sand modified expansive soil have been implemented in this paper.Undisturbed soil and expansive soil mixed with 10%,20%,30%,40%,50% of weathered sand have been carried out expansive force experiment on the lever type standard consolidation apparatus.Undisturbed soil and expansive soil mixed with 10%,20%,30%,40%,50% of weathered sand have been done loaded swelling ratio experiment according to 0 kPa,12.5 kPa,25.0 kPa,37.5 kPa,50.0 kPa,75.0 kPa six stage loading on lever type standard consolidation apparatus.Experimental results show that with the increasing of dosage of weathered sand,expansive force decreases significantly;the expansive ratio of the same sand ratio between the overlying load logarithm is linear relationship;under the same overburden loads,the expansive ratio of swelling soil mixed with weathered sand firstly increases and then decreases.Through the experimental research,the possible deformation of different depths can be inferred.Furthermore,the needed thickness of expansive soil can be rationally designed in engineering.