A strength reduction method based on double reduction parameters and its application

YUAN Wei(袁维), BAI Bing(白冰), LI Xiao-chun(李小春), WANG Hai-bin(汪海滨)

(State Key Laboratory of Geomechanics and Geotechnical Engineering (Institute of Rock and Soil Mechanics,
Chinese Academy of Sciences), Wuhan 430071, China)

Abstract:In the traditional strength reduction method, the cohesion and the friction angle adopt the same reduction parameter, resulting in equivalent proportional reduction. This method does not consider the different effects of the cohesion and friction angle on the stability of the same slope and is defective to some extent. Regarding this defect, a strength reduction method based on double reduction parameters, which adopts different reduction parameters, is proposed. The core of the double-parameter reduction method is the matching reduction principle of the slope with different angles. This principle is represented by the ratio of the reduction parameter of the cohesion to that of the friction angle, described as η. With the increase in the slope angle, η increases; in particular, when the slope angle is 45°, η is 1.0. Through the matching reduction principle, different safety margin factors can be calculated for the cohesion and friction angle. In combination with these two safety margin factors, a formula for calculating the overall safety factor of the slope is proposed, reflecting the different contributions of the cohesion and friction angle to the slope stability. Finally, it is shown that the strength reduction method based on double reduction parameters acquires a larger safety factor than the classic limit equilibrium method, but the calculation results are very close to those obtained by the limit equilibrium method.

Key words:double reduction parameter; strength reduction method; matching reduction principle; slope stability