ABSTRACT
To study the anisotropy of deformation and strength of intact loess in the western area of Henan Province and the influence of loess anisotropy on the deformation of tunnel surrounding rock, the intact loess was sampled from the Kole Bay tunnel in vertical and horizontal directions. The difference in deformation and strength parameters between horizontal and vertical directions of intact loess was analyzed through laboratory consolidation and triaxial shear tests. The test results show that the anisotropy of loess in the western area of Henan Province is remarkable. Under the same normal pressure, the compressibility of loess in the vertical direction is higher than that in the horizontal direction. The modulus of deformation in the vertical direction is 1.8 times the modulus of deformation in the horizontal direction. The cohesion in the vertical direction is 35.46% higher than that in the horizontal direction, and the friction angle in the vertical direction is 5.05% higher than that in the horizontal direction. The difference in shear strength parameters is mainly reflected in cohesion. Numerical simulation was used to study the effect of loess anisotropy on the deformation of the tunnel surrounding the rock. The results show that the tunnel vault settlement of the anisotropic model is larger than those of the isotropic model under the same working conditions. The isotropic model may underestimate the effect of tunnel surrounding rock deformation, and the anisotropic model is more accurate in describing the mechanical behavior of the loess tunnel excavation process.
