MECHANICAL DEFORMATION CHARACTERISTICS AND CONSTITUTIVE MODEL OF FIBER YARN REINFORCED LOESS

Fibre yarn is formed by loosening,carding and cutting waste synthetic textile polyester fabric. A certain proportion of fibre yarn was added to plain loess,which formed fibre yarn reinforced loess. The uniaxial compression test and triaxial shear test of fiber reinforced loess were carried out using servo hydraulic loading double chamber high pressure triaxial apparatus. The compressive deformation and stress-strain characteristics of fiber yarn reinforced loess were systematically analyzed. The results showed that with the increase of fiber yarn proportion in plain loess,the compressive deformation decreases. The yield pressure of fiber yarn reinforced loess was determined. The yield pressure increased with the increase of fiber yarn proportion in plain loess. According to the stress-strain relationship of fiber yarn reinforced loess in triaxial shear test,it was found that under the same consolidation pressure,with the increase of fiber yarn proportion in plain loess,the reflected shear stress also increased. With the increase of consolidation pressure,the shear stress increased with the increase of fiber yarn blending ratio. According to the stress-strain relationship of fiber yarn reinforced loess in triaxial shear test,a comprehensive index—fiber reinforced index I_r was constructed. The index I_r could reflect the actual reinforcement effect of liber yan reinforced loess. The cohesive force was hyperbolic with the increase of the index I_r. The internal friction angle kept constant with the increase of the index I_r. Based on modified Cambridge model,according to the difference of the index I_r,the isotropic compressive ball stress and critical state line with the change of fiber reinforced index I_r was determined. Taking plastic volume strain as hardening parameter,the elastoplastic constitutive model of fiber yarn reinforced loess was derived. After testing validation,it was proved that the constitutive model can reasonably describe the mechanical deformation characteristics of fiber yarn reinforced loess.