SAFETY AND RELIABILITY OF ANCHORED BULKHEAD WALLS

This paper utilizes the classical approach of free earth support method along with the Coulomb theory of lateral earth pressure as applied to the design of anchored bulkheads. General design equations are developed and presented in a graphical form to provide: (a) depth of pile penetration; (b) maximum bending moment on the wall; and (c) force in the anchor rod. To represent true field situations, the factors affecting the design are considered as random variables. Through a first order expansion about the mean, the mean and variance of the design outputs are derived in terms of the variations in the soil parameters, water level and loading conditions. Using appropriate probability distributions along with the mean and variance of the design outputs the overall wall reliability is assessed. The suggested design provides a safe penetration depth, reduced moment and anchor force based on reliability theory. Furthermore, the results indicate that in some cases, depending on the variabilities of the design factors, a safety factor of 1.5 produced a low reliability and, thus, an unsafe design.