Mechanism and risk evaluation of sliding flow triggered by liquefaction of loess deposit during earthquakes

The large-scale sliding disaster of the saturated low angle soil layer caused by the Palu M_w7.5 earthquake in Indonesia in 2018 has an important warning for the sliding flow triggered by liquefaction of loess deposit during earthquakes in the loess areas. To study the mechanism of large-scale sliding with low slope angle triggered by the liquefaction of the loess deposit during earthquakes, a series of field investigations, in situ tests including SPT and shear velocity tests, dynamic triaxial tests, and SEM tests are conducted based on the in-depth analysis of typical earthquake-induced liquefaction disasters in loess areas. The characteristics and mechanisms of liquefaction of the saturated loess are revealed. The simplified and detailed evaluation methods for the liquefaction of saturated loess sites are proposed. Moreover, on the basis of numerical simulation and theory analysis, the sliding conditions, kinematics and dynamic characteristics of the large-scale sliding flow triggered by the liquefaction of loess deposit during earthquakes are studied. The mechanism of the large-scale sliding of loess deposit is expounded. The prediction model for the sliding distance and disaster range of the large-scale sliding flow triggered by the liquefaction of loess deposit during earthquakes is constructed. The probabilistic risk assessment method for the liquefaction sliding disasters is proposed, and the risk zoning maps of the large-scale sliding flow triggered by the liquefaction of loess deposit with different exceedance probabilities in the Loess Plateau are compiled. Besides, the passive and active prevention methods as well as the comprehensive monitoring and early warning methods are proposed. The results may provide a theoretical basis for the risk assessment, prevention and mitigation of the large-scale sliding flow triggered by liquefaction of loess deposit during earthquakes in the loess regions.