A design analysis for anchoring soil and fractured rock masses prone to circular failur

ABSTRACT

This analytical study considers anchoring of soil and highly fractured rock masses under circular failure conditions. A new formula is developed to calculate the total weight of the failing material, and its consequent total normal and tangential forces acting on the circular failure zone utilizing the Fellenius method. Also, the driving moment is calculated based on the most unstable conditions using Janbu's charts for critical toe circles. Comparison is made between the above noted method and that of Kotter's differential equation for calculation of the safety factor. An analytical solution is suggested to determine the optimum anchor inclination, related either to safety factor or minimum support requirement. Finally, a practical example is given to clarify the proposed method under active conditions.