Introduction on Factors of Safety for Cantilevered Sheet Pile Walls :
Methods to apply a factor of safety to the geotechnical design of a cantilevered sheet pile wall are described here. For types and design processes see Sheet Pile Walls Topic.
Concepts and Formulas of Factors of Safety for Cantilevered Sheet Pile Walls:
There are usually three methods:
Factored depth of embedment
This is the method mostly used in practice due to its simplicity and easiness; calculate the value of the depth of embedment (D) using static equilibrium and the best estimate of strength parameters (φ, c). Then, calculated value of D is arbitrarily increased by 20 to 60%:
usually 1.2 - 1.4 for granular soils
usually 1.4 - 1.6 for cohesive soils
Round up D design to next whole foot.
Factored earth pressure
In this approach, use factored Kp (called K*p) in place of Kp to determine net pressure diagram:
In this approach
Factored strength parameters
This approach is super conservative; in this approach, use factored strength parameters (φ*,c*) in place of (φ,c) to determine K*p and K*a.
Determine net pressure diagram using K*p and K*a in place of Kp and Ka: