Influence of hydraulic conductivity of tension crack on the stand-up time of unsupported vertical trenches in unsaturated soils

ABSTRACT: It is well known that tension cracks have an adverse impact on the stability of a slope since it reduces the resistance to slope failure due to the decrease in slip surface. In addition, when rainfall infiltrates into a tension crack, the strength of a soil in the vicinity of a tension crack significantly decreases, which leads to sudden failure in a slope. However, limited studies have been undertaken to investigate the influence of rainfall infiltration into tension cracks on the stability of unsupported trenches in unsaturated soils. In the present study, a series of numerical analyses are conducted to estimate the stand-up time of unsupported vertical trenches excavated in an unsaturated glacial till (i.e., Indian Head till). Tension cracks were simulated by adopting two different approaches: i) material with zero strength and its own hydraulic conductivity function and ii) void space. Stand-up times obtained with these two approaches are compared and the results are discussed.