Stability Analysis of the Soil Slope with Cracks Considering the Upper Slope Inclination

Cracks often adversely influence the slope stability. Crack development is not only related to the soil properties but also depends on the slope geometry. To study the influence of the inclination angle of an upper slope on the stability of slopes with cracks, this study considered an upper non-horizontal slope with cracks as a research object using the kinematic approach of limit analysis and logarithmic spiral rotating mechanism of plane strain. The effects of static and seismic forces were considered, and the velocity compatible motion field and corresponding energy balance equation were developed. Three different types of calculation models were employed, namely, unspecified depth and location of cracks, cracks with known depth but unknown location, and cracks with known location but unknown depth. The stability factor of the soil slope with cracks under different slope parameters (slope angle β, inclination angle of the upper slope α, and internal-friction angle φ) and different seismic forces (kh=0.1, 0.2, and 0.3) was calculated using nonlinear sequential quadratic programming. The results demonstrate that the greater the inclination angle of the upper slope, the greater the percentage reduction in the slope-stability factor. The overvaluation of the stability factor is as high as 15%, if the upper slope inclination angle. is not considered. The larger the seismic force, the more significant the influence of the inclination angle of the upper slope on the percentage reduction in the stability factor. With the increase in the inclination angle of the upper slope, the depth of the critical crack gradually increases, and its position gradually moves far from the crest. Only when the crack is within a certain range does the stability factor decrease, and this range increases owing to the effect of the inclination angle of the upper slope and the seismic force. Under static forces, as the slope angle increases, the reduction percentage in the stability factor first increases and then decreases. In comparison with the results of OPTUMG2, the stability analysis of soil slopes with cracks considering the upper slope inclination angle in this work is reasonable. © 2021, Editorial Department of China Journal of Highway and Transport. All right reserved.