Mechanical Properties and Constitutive Model of Expansive Soil Improved by EICP

Abstract

In order to study the improvement effect and mechanical properties of expansive soil under different EICP treatment rounds, a consolidated drained triaxial test with EICP treatment times and confining pressure as variables was carried out.The stress-strain curve, Mohr-Coulomb strength envelope, shear strength index c and φ were calculated and plotted according to the experimental data. Finally, the Duncan-Chang model was used to explore the influence and relationship of EICP treatment times on the parameters of the constitutive model.The results show that : (1) Under the same confining pressure, the peak deviatoric stress of the expansive soil improved by EIPC increases and increases with the increase of the number of treatment rounds. (2) Compared with the unmodified expansive soil, the shear strength indexes c and φ of the expansive soil after EICP treatment are improved, and also increase with the increase of the number of treatment rounds. (3) When the number of treatment rounds increases to 7 times, the improvement effect is significantly weakened, indicating that there is an optimal number of treatment rounds when EICP improves expansive soil. (4) The triaxial test data were analyzed by the Duncan-Chang constitutive model. It can be obtained that the number of EICP treatment rounds h has an effect on the parameters of the Duncan-Chang model : as the number of treatment rounds increases, the parameters a and b gradually decrease ; the initial tangent modulus Ei increases gradually ; the parameters K and n increase gradually. (5) Through data fitting, the number of EICP treatment h was connected with the Duncan- Chang model parameters K, n, c, φ, and brought into the Duncan-Chang tangent modulus formula, and the modified tangent modulus equation of expansive soil under EICP treatment was obtained.