Forewarning of Static Liquefaction Landslides

Static liquefaction failure and the ensuing flow slide of slopes have produced significant damages to structures and even loss of lives. Based on a very large number (1,632) of laboratory shear tests on cohesionless soils and mine tailings, a triggering excess pore-water pressure ratio (ru,tr) is introduced in this study above which static liquefaction failure could occur. The effects of variations in the direction and relative magnitudes of principal stresses associated with different modes of shear, ground slope, and boundary conditions are incorporated for predicting ru,tr. The findings compare favorably with pore-water pressures measured just prior to the onset of failure in a field case study and several flow-slide flume experiments. The triggering pore pressure ratio suggested in this study can be employed as a more tangible criterion for detecting liquefaction triggering and landslide warning in instrumented slopes of cohesionless soils and mine waste tailings. (c) 2020 American Society of Civil Engineers.