Evaluating the effects of irregular rock block macro-structure characteristics on the stability of soil-rock slopes

Irregular rock blocks with diverse macro-structures characteristics are very common in practical soil-rock slope engineering. The aim of this paper is to investigate the stability of soil-rock slope using strength reduction limit analysis method. More than 1400 2D stability analyses were performed on soil-rock slope models with different polygonal rock block shapes and with major axis inclination angles varying between 0 degrees and 180 degrees. A stochastic generation method based on the function distribution was introduced to consider the spatial random distribution of rock blocks. For each kind of polygonal shape and major axis inclination, ten different rock blocks arrangements had been made. The results showed the major axis inclinations of irregular rock blocks have significantly impact on the slope stability. When the angle between the major axis and the slope surface is nearly maximum, the safety factor of soil-rock slope tends to be a maximum. In addition, two forms of shear zone divergence/ penetration development in soil-rock slopes have been summarized,namely detouring/ rounding or containing/holding rock blocks. Furthermore, smaller number of edges make it more frequent for rock blocks to undergo friction-slip during shear deformation, resulting in a higher safety factor.