Experimental Study On The Characteristic Of Improved Expansive Soil With Lime-Basalt Fiber

Expansive soil has the characteristics of high plasticity,multi fractured, expansion of water,shrinkage is a special Kind of unsaturated cohesive soil. Expansive soil is in different depth,in different forms of layers,which is widely distributed in all parts of the country,at the same time,which brings all Kinds of the inconvenience of construction,the bad properties of expansive soil bring the inestimable economic loss to the safety of construction. Highway comes into our daily lives imperceptibly with the improvement of economic level,meanwhile which leads to the probability of highway that especially in the area of scarce resources increases year by year. The modified expansive soil has been filled into the subgrade in the scarce resources of area,due to the significant characteristics swelling and shrinkage of expansive soil,so the need of modified expansive soil can be used in practical engineering,through a series of the indoor experiments on expansive soil in this thesis,test results show that:(1)The optimal water content of expansive soil has been found to increase with the rate of lime addition increases, the maximum dry density increased with the amount of lime decreases through analyzing the compaction test on the expansive soil. The modified expansive soil has been in a state of weaken sensitivity to the moisture content,the nature of modified expansive soil brings great convenience to the construction site.(2)Expansive soil with lime were 0%, 2%, 4%, 6%, 8%,which has been a series of laboratory tests include direct shear test, unconfined compressive strength test and three axial test. Tests results show that there was a growing tendency of the strength of modified expansive soil with the addition of lime. The addition of lime was 6% made the strength of modified expansive soil achieved the best state.(3)Expansive soil with basalt fiber were 0%, 0.1%, 0.3%, 0.5%,which has been a series of laboratory tests include expansion force test, consolidation test and so on. The tests results show that basalt fiber has not played a role in the consolidation of the expansive soil,basalt fiber play a constraint on the expansibility of expansive soil, but the content of fiber is not more, the effect is better, the addition of fiber was 0.3% made the modified expansive soil achieved the best state.(4)Dry density of expansive soil were 1.75g/cm~3, 1.85g/cm~3, moisture content were 21%, 23%, 25%. The different contents of limestone and basalt fiber have been added into the expansive soil, modified expansive soil has been done three axis test. The test results show that lime made the dry density of expansive soil was 1.85g/cm~3 been in the better state and ductility of modified expansive soil has been in the better conditions. The addition of basalt fiber was 0.3% made the moisture content of expansive soil was 23% ductility been the better conditions, but the strength of modified expansive soil has not worked.