Evaluation of Pore Water Pressure Prediction Methods under Rapid Drawdown: Case Study of the Pilarcitos Dam Failure
Publication: Geo-Extreme 2021
ABSTRACT
Work in this study utilizes coupled, partially coupled, and uncoupled transient seepage analysis approaches to investigate the Pilarcitos Dam failure due to the rapid drawdown (RDD) condition. The Pilarcitos Dam is modeled using the finite-element (FE) software PLAXIS utilizing nonlinear advanced elastic–plastic constitutive relation. The modeled embankment is subjected to rapid drawdown, and the stability factor of safety (FS) is determined using the strength reduction method (SRM). The uncoupled seepage/stability approach is also applied whereas the partially coupled seepage analysis and the subsequent stability analysis are performed using FE program SEEP/W and limit equilibrium (LEM) software SLOPE/W, respectively. Results indicated that the use of coupled analyses leads to more realistic estimation of pore water pressures after RDD, as compared to the partially coupled and uncoupled analysis approaches. In this case, only the coupled analysis approach yielded representative FS and maximum depth of potential slip surface that reflect conditions observed for Pilarcitos Dam failure. In addition, the results indicated that the estimated time for complete dissipation of pore pressure after drawdown is significantly higher for uncoupled and partially coupled analyses as compared to the coupled analysis approach.
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Geo-Extreme 2021
Pages: 141 - 150
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© 2021 American Society of Civil Engineers.
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Published online: Nov 4, 2021
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