Numerical analyses of embankment dams containing plastic concrete cut-off walls using finite difference method (A case study: The Karkheh Embankment Dam)

Yadolah Pashang Pisheh Yadolah Pashang Pisheh,Seyd Majdeddin Mir Mohammad Hosseini Seyd Majdeddin Mir Mohammad Hosseini

doi:10.30574/gjeta.2021.9.3.0176

Yadolah Pashang Pisheh Yadolah Pashang Pisheh, Seyd Majdeddin Mir Mohammad Hosseini Seyd Majdeddin Mir Mohammad Hosseini

Open Access

https://doi.org/10.30574/gjeta.2021.9.3.0176

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Abstract

In this paper, numerical analyses have been performed on the Karkheh embankment dam with a clayey core and plastic concrete cut-off wall during construction, impounding, and permanent seepage stages. The dam has 127 meters height and is located in a high seismic hazard zone in Iran. Different stages of construction, water impounding, and steady state seepage were modelled and analyzed using the hyperbolic and Mohr-Coulomb models with the two dimensional finite difference method (FDM). So, nonlinear analyses were performed using FLAC 2D to investigate the settlements and the pore water pressure changes in different zones of the dam during above-mentioned stages and the results were compared to those of the other studies. The results show that at the end of the construction stage, the maximum settlement equal to 1.45m occurs inside the clay core at the height of 65m. Then, after impounding of the reservoir and steady state stage, the maximum magnitude of the horizontal deformations occurs in the downstream of the dam equal to 0.55m; however, these magnitudes reach to 0.17m at the crest of the dam. Moreover, it was shown that the maximum horizontal displacement of the plastic concrete cut-off wall has happened at the top of the wall in the clay core which is in a good agreement with the other studies’ result.

Highlights

Embankment dams provide a life-sustaining resource to people in all regions of the world
Employing cut-off walls of plastic concrete material is one of the most important and effective methods used for seepage control and remediation in weak foundations of embankment dams
The main purpose of this paper is to study the mechanical behavior, i.e., the settlements and the pore water pressure changes, of different zones of an embankment dam including its body, mixed clayey core, and plastic concrete cut-off wall

Summary

Introduction

Embankment dams provide a life-sustaining resource to people in all regions of the world. Plastic concrete as a proper material meets essential requirements for dams’ cut-off wall construction including strength, stiffness, and impermeability. These features are crucial for the prevention of the earthquake geo-hazard’s disasters in geotechnical structures [2, 3] especially, those located in seismic zones [4]. The aggregates’ size is usually limited to a certain value and some amounts of bentonite are added to the mixture of the concrete.

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