Influence of cracks on the stability of a cracked soil slope

Cracks are present widely in soil slopes and can decrease the stability of the slopes through three effects. First, cracks provide preferential flow channels which increase the soil permeability and decrease the soil strength. Second, water-filled cracks exert an additional driving force on the slope. Finally, cracks can form a part of the critical slip surface that has no shear strength. The objective of this paper is to study the influence of cracks on the stability of a cracked soil slope subjected to rainfall infiltration. The effects of crack location, crack depth and rainfall intensity on the stability of the cracked slope are explored. Seepage and stability analysis are conducted for the saturated-unsaturated cracked soil slope using SEEP/W and SLOPE/W. Results show that the pore water pressure distributions in the slope and the factor of safety (FOS) of the slope are affected by the presence of cracks. When the crack is shallow, the changes in pore water pressure and FOS are small. When the crack is deep and penetrates an embedded coarse layer in the slope, pore water pressures increase significantly and the FOS decreases sharply. The decrease in FOS is larger when the crack is located at the crest of the slope than in the middle of the slope. Results also indicate that the stability of the cracked soil slope is worse when it is subject to a long rain with a small intensity than to a short period of intense rainstorm.