Health monitoring and dynamic analysis of an earth-fill dam at the stage of first impounding: case study—Siahoo dam of Iran

Abstract

First impounding of the earth-fill dams is considered as one of the most critical stages of these earth structures during their lifespan such that it demands careful monitoring of the dam’s safety. In this study, behavior of Siahoo dam, an earth-fill dam in Iran, is evaluated by numerical modeling at the stage of first impounding to (1) back-analysis and calibration of the numerical model using data of instrumentation measurements, gathered during the dam construction. (2) Determine the optimized plan of the dam’s first impounding so that the dam safety is secured against hydraulic fracturing. (3) Predict the displacements of the dam in the future under seepage and consolidation using the calibrated numerical model. (4) Analyze the dam under seismic loading condition. The material properties were chosen through a two-step procedure based on numerical simulation of laboratory tests in the software and calibration between the stress–strain analysis of the dam and instrumentation measurements at the end of construction stage, so that the real behavior of the dam can be represented. To find the maximum rate of dam’s first impounding in safe condition, a sensitivity analysis was performed assuming eight number of impounding scenarios. Having performed the steady-state seepage analysis, seismic loading was applied using the equivalent linear method and the permanent displacements were predicted using the method of Newmark sliding blocks. Liquefaction analysis was also performed to recognize liquefiable zones of the foundation. Finally, stress redistribution analysis was carried out to estimate the post-earthquake displacements.