| Loess is a special soil with strong structure,and the existence of structure causes loess to have special wetting characteristics and seismic collapse characteristics.In this paper,the dynamic characteristics of the original,remodeled and original saturated loess were tested step by step by using the hollow cylindrical torsion shear,and the single-stage loading liquefaction test was carried out for the saturated loess,and the following conclusions were mainly obtained:(1)Under the action of cyclic load,the dynamic stress-strain relationship curve of the original loess and the remodeled loess are hyperbolic,of which the size of the consolidation confining pressure and the moisture content have a significant impact on the dynamic characteristics of the two loesses,which is reflected in the fact that the dynamic shear strength increases with the increase of the consolidation confining pressure and decreases with the increase of the moisture content.(2)The dynamic characteristics of loess include two basic parameters of dynamic shear modulus and damping ratio,and the change law of dynamic shear modulus with consolidation confining pressure and moisture content is analyzed,and the range of changes of the original state and remodeling loess damping ratio is determined,and the upper and lower limits of the change of loess damping ratio are fitted.(3)Through the liquefaction test of saturated loess,the amplitude of water pressure with shear strain,dynamic load frequency,consolidation confining pressure and consolidation stress ratio of loess dynamic pore pressure were analyzed,and a mathematical model of the increase of pore pressure of saturated loess with consolidation confining pressure was established.(4)Based on the comprehensive structural formula idea,the definition method of the constitutive index is compared,and the dynamic structure index of the initial structural parameters of the loess under dynamic load is established,and the change law of the dynamic structure index with the moisture content and the consolidation confining pressure is analyzed.(5)The initial shear modulus and maximum dynamic shear stress formula of loess considering the influencing factors of consolidation confining pressure,moisture content and dynamic structure were constructed,and introduced into the Hardin-Drnevich viscoelastic model,and a modified Hardin-Drnevich viscoelastic model considering the structure of loess was established. |
