Abstract: Tensile cracks influence the stability of loess slopes, which has become a key problem in the stability analysis of slopes and even the study of loess landslides. The previous studies based on the elastic semi-infinite spatial theory aren't in accordance with the real strain state of soil unit near the tip of cracks. Based on the soil mechanics for unsaturated soils and the maximum tensile strain strength theory, a new equation of limit depth of cracks is established. In the equation, the soil-water characteristic curve variables are obtained via pressure plate extractor tests. Mechanism of the tension cracks and influence of the variables on tension cracks is also analyzed. The comparison between results of the equation and actual values show that are much closer each other.

Key words: tensile cracks, ultimate depth, loess slopes, infiltration, unsaturated soil