TRIAXIAL CREEP PROPERTIES OF FIBER REINFORCED EXPANSIVE SOIL

Studies on the properties and improvements of expansive soil have drawn more and more attentions because of many engineering accidents caused by deformation of expansive soil. In order to investigate the creep characteristics of fiber reinforced expansive soil, unsaturated triaxial creep tests are carried out with the consideration of the influence of water content and reinforcement ratio of basalt fiber mixed into the expansive soil. Long-term strength of the fiber reinforced expensive soil is analyzed through isochronous stress-strain curves. Meanwhile, Mesri creep model is established and verified. The main conclusions are as follows:By comparing strain-time curve, it finds that the fiber reinforced expansive soil has an obvious role on reducing creep deformation. However, there exists an optimal reinforcement rate. If fiber content surpasses the optimal reinforcement rate, the creep effect cannot be significantly decreased. The creep properties of the fiber reinforced expansive soil increase as the moisture content decreases. They have the optimum moisture content. If less than the optimum moisture content, the creep effect cannot be significantly increased. Isochronous stress-strain curves can be obtained from the strain-time curve at different load levels. The long-term strength of the samples can be figured out according to the inflexion point of isochronous stress-strain curves. Long-term strength of expansive soil can be significantly improved by fiber reinforcement. In the test, the long-term strength of 0.4% reinforced expansive soil is improved by 26.7% compared with pure soil under the same condition. The long-term strength of 0.6% reinforced expansive soil is improved by 23.3%. Mesri creep model can generally reflect the triaxial creep characteristics of fiber reinforced expansive soil.