Dynamic constitutive relationship of lignin-modified loess

To effectively improve the dynamic vulnerability of loess, lignin is selected as the environmentally friendly material to enhance the loess. Based on the dynamic triaxial tests, the dynamic constitutive relationship of lignin-modified loess is studied. A Hardin-Drnevich modified model considering the lignin content is discussed. The results show that the backbone curves of the modified loess with different lignin contents have significant differences. Under the same dynamic stress, the dynamic strain of modified loess with lignin content of 1% is the smallest. The hysteresis curves and the damping ratio-dynamic strain curves of the modified loess with different lignin contents have significant differences. The long axis of the hysteretic cycle of modified loess with lignin content of 1% is shorter, the shape is narrower, and the area is smaller. The damping ratio of the modified loess increases firstly with the increase of the lignin content, and it has a peak when the lignin content is 1%. The dynamic constitutive relationship of the lignin-modified loess conforms to the Hardin-Drnevich hyperbolic model, and the lignin content m can be introduced into the model to obtain a well-correlated Hardin-Drnevich modified model. The lignin can effectively improve the dynamic deformation resistance, seismic performance and dynamic stiffness of loess. However, the continuous increase of lignin content doesn't lead to the continuous improvement of dynamic characteristics.