RESEARCH ON THE INFLUENCE ON EXPANSIVE SOIL CHARACTERISTICS BY DIFFERENT MIXING RATES OF WEATHERED SAND

Based on defects of expansive soil modification methods,a physical improvement method with which weathered fine sand was mixed with expansive soil was proposed.Grain size distribution test,liquid limit and plastic limit test,activity index test and specific gravity test of different proportions of weathered sand modified expansive soil were done.Experiments results showed that with the increase in the proportion of sand,activity index fell sharply and liquid limit and plastic limit were changed significantly.Free swelling ratio test,loaded swelling ratio test,swelling ratio test and expansive force test of different proportions of weathered sand modified expansive soil were done.With the increase in the proportion of sand,expansive characteristics of expansive soil were significantly inhibited.At last,direct shear test,unconfined compressive strength test,CBR test and modulus of resilience test of different proportions of weathered sand modified expansive soil were done.The laws and influence of different proportions of weathered sand modified expansive soil were discussed.Test results indicated that sand could better improve expansive soil engineering characteristic indexes,effectively inhibit expansive characteristic of expansive soil,improve the mechanical strength of expansive soil.Each index of weathered sand modified expansive soil could meet roadbed filling requirements.