Calculation Method of Stability Coefficient of Perilous Rock Based on the Limit Equilibrium Theory

As a geological disaster in mountain regions, perilous rock on cliffs and/or steep slopes can be classified as three categories, sliding perilous rocks, toppling perilous rocks and falling perilous rocks. In the stability analysis of perilous rock, the important work is to acquire the stability coefficient of perilous rock under action of certain load combination. Based on the appearing frequency of loads acting on perilous rock, three load combinations are designated. Moreover, two experiential formulae to calculate shearing strength parameters, the average cohesion and the average friction angle of dominant fissure, are established by experiments in laboratory. Further, formulae to calculate three categories of perilous rocks are derived in detail from the limit equilibrium theory, widely and effectively applied since 2000 in the area of the Three Gorges Reservoir, China.