Research on Shear Strength Index of Expansive Soil Modified by Weathered Sand

Through the comparative analysis of the influences of expansive soils improved by lime,cement,coal ash on the shear strength index,impact of the weathered sand improved expansive soil on shear strength index was studied.The shear of the expansive soil mixing with different proportion of weathered sand was tested.The results showed that the expansive soil shear strength could be effectively improved after weathered sand was incorporated into expansive soil;its cohesive force will decrease gradually with the increase of sand addition proportion;and the angle of internal friction would firstly increased and then decreased along with the increase of sand addition proportion.The expansion characteristic was tested after adding different proportion of weathered sand,and the conclusion could be drawn as followings: blending weathered sand could effectively inhibit the expansion and contraction of expansive soil,the swell-shrink rate of the improved expansion soil was lower than 0.7%,therefore,it could reach the standard of packing filling.With respect to comprehensive consideration of the influence of the sand addition ratio and moisture content on expansive soil shear strength parameters,it could be concluded that when sand addition proportion was up to 30% and the moisture content was 10%,the shear strength of the expansive soil that added with weathered sand would achieve the best parameter.