Delay phenomenon of shallow slope failure triggered by rainfall and its correlation with soil parameters

The effect of rainfall on the slope may continue and the most unstable state may occur after rainfall stops. This phenomenon was described as the delay phenomenon. According to the infiltration characteristics of rainwater in the soil, two representative models of landslides occurring after rainfall were set up to illustrate the mechanisms of the delay phenomenon. The concept of critical moment was defined. The relationship between the delay phenomenon and soil parameters was analyzed using numerical analysis method. The results show that the delay phenomenon has a direct relationship with soil permeability parameters and soil strength parameters. The soil slope tends to have failure during rainfall when the permeability coefficient is larger than 1×10-4 m/s and air intake and discharge capacity are strong. The slope tends to be in the most unstable state when the permeability coefficient is between 1×10-7 m/s to 1×10-6 m/s. When the soil strength parameters are determined, the critical moment of the slope decreases firstly and eventually becomes stable with the increase of the permeability coefficient. The critical moment of the slope increases firstly and tends to be stable with the increase of the soil strength parameters when the permeability coefficient is determined. Soil permeability is the major influencing factor of the delay phenomenon. When permeability is fitted, soil strength parameters have dominant efficient when the soil strength is low. © 2018, Central South University Press. All right reserved.