Study on the creep behaviours and the improved Burgers model of a loess landslide considering matric suction

Loess landslides frequently occur in the northwest area of China, leading to serious damage to the society and economy. Under the effects of rainfall and groundwater seepage, the stress-strain behaviours of Malan loess landslides are closely related to the saturated-unsaturated state of slide mass. Hence, it is of great significance to study the creep behaviours of Malan loess considering matric suction. First, the sliding-zone soil of a typical Malan loess landslide is collected to carry out tri-axial creep tests with a confining pressure of 100 kPa and diffident matric suction values of 20, 50 and 80 kPa. Then, a stress-suction-strain-time model (an improved Burgers model) is established by connecting a nonlinear dashpot element in series with the Burgers model and combining this with the functional relationship between the viscoelastic modulus and matric suction. The results show that (1) the Malan loess has obvious creep behaviours with viscoelastic and viscoplastic creep properties, (2) the long-term shear strength of Malan loess increases along with the increase in its matric suction, and (3) the improved Burgers model can more accurately describe the unsaturated creep behaviours of Malan loess with matric suction compared to the traditional Burgers model.