Safety and stability control of Mashkid Olia earth dam based on response surface optimization methodology (case study)

Abstract

In this paper, a specific earth dam in Iran as a case study was selected to introduce a new approach to numerical modeling and safety analysis. First, the dam body and its foundation were accurately modeled in PLAXIS 3D. The datum was collected from official reports. A specific section of the dam and foundation in which some instruments were placed was selected and a comparison of settlements in different parts was made between instrument data and finite element method (FEM) analysis. Since there was no favorable fitting, back analysis seemed to be crucial. Response surface methodology (RSM) was adopted to make some equations that can replace the hardening soil model and be easy to be optimized for desired settlements. Since the runs in the FEM software, PLAXIS 3D would take considerable time and energy, a new approach to use RSM was introduced which is called two-step RSM. It could be seen that if sensitivity analysis is performed on a linear RSM model at first, the second-order model of soil behavior can accurately be predicted with much less effort. Some statistical tests such as \({\sigma }^{2}\) and \({R}_{adj}^{2}\) were considered to prove the adaptability of the new method. Two second-order RSM equations, for both core and shell, were optimized with the help of a genetic algorithm. The results suggested an acceptable fit when compared to instrumental data. Four water level scenarios were selected to run a Safety analysis on the most significant section of the dam which yielded the factors in the favorable ranges.

Graphical Abstract