A simple approach for probabilistic internal stability analysis and design of reinforced soil walls

ABSTRACT: This paper explains probabilistic analysis and design for simple internal stability limit states for mechanically stabilized earth (MSE) walls using the example of steel grid reinforced soil walls. The general approach uses a closed-form solution for reliability index which is easily implemented in a spreadsheet and thus eliminates the need for Monte Carlo simulation. A novel feature of the formulation is that it includes uncertainty in the choice of nominal values [which is consistent with the notion of level of understanding that appears in the Canadian Highway Bridge Design Code] and the underlying accuracy of the load and resistance models that appear in each limit state equation using bias statistics. The paper demonstrates how bias statistics for tensile load and pullout model accuracy can be gathered from load measurements recorded from instrumented walls and found in laboratory pullout box test databases. The concepts are general and can be applied to any soil-structure interaction problem which can be expressed by a simple linear limit state performance function and for which bias statistics are available.