Multi-Hazard Response Simulation of Levees Using Design of Experiments and Response Surface Methodology

Abstract

This paper presents a methodology for a combined flood and earthquake response simulation of levees. The methodology also incorporates the effect of inherent uncertainties in factors such as levee construction and design as well as flood and earthquake hazard on the response of the levee. The flood and earthquake response of levees is simulated using QUAKE/W and SLOPE/W programs. A levee model is defined using geometric parameters such as levee height, slopes, etc. which conform to the US Army Corps of Engineers levee design specifications. Several combinations of hazard levels can be specified using different flood levels and earthquake time histories. The factor of safety of the upstream and the downstream slope are used as damage indices. An attempt to simulate the response of all possible combinations would require thousands of computational runs. This unrealistic task is avoided by performing only a few model simulations, which are selected by a systematic procedure called the Design of Experiments (DOE) technique. Various model parameters that influence the levee response are first identified. The DOE technique is used to select only a few important combinations of these parameters. The Response Surface Methodology (RSM) is used to create metamodels of damage indices. In RSM, the damage indices are approximated by response surface regression equations in which the model parameters are used as predictor variables. The response of any combination of parameters can then be calculated using these regression equations. Also, probability distributions are assigned to model variables and the resultant probabilistic response is computed by performing a Monte Carlo Simulation (MCS) on the response surface regression equation. The entire analysis is integrated in a spatial framework where the response simulation can be viewed from ArcGIS interface. The methodology is used to analyze real inventory data for the levees near Memphis, which may experience simultaneous damage from the Mississippi river flood and New Madrid Zone earthquake.