System Reliability Analysis of Soil Nail Walls against Facing Failures

Abstract

The facing design of soil nail walls against flexure, punching shear, and headed-stud tensile limit states has been rarely studied within the reliability-based design framework. This study presents reliability analyses of both temporary and permanent soil nail walls against facing limit states using the default and improved Federal Highway Administration (FHWA) facing load models and the default FHWA resistance models. With consideration of model uncertainty and variability of soil shear strength, reliability analyses are conducted on the facing that is first designed to achieve a set of prescribed factors of safety using conventional deterministic allowable stress design approach. Results show that the current deterministic design practice typically leads to a facing design with minimum reliabilities of 1.0–2.5 against the limit states. A factor of safety of 3–4 is warranted for a minimum reliability of 3.54. The punching shear limit state has the least reliability. Statistical correlations among the limit states are investigated and the facing system reliability is evaluated, where system reliability is defined as the reliability that none of the three limit states is reached. Finally, sensitivity analyses are carried out to examine the influences of several design parameters on the computation outcomes of reliability.