Analysis of foundation sliding of an arch dam considering the hydromechanical behavior

doi:10.1007/s11709-012-0142-1

Front Struc Civil Eng

2012, Vol. 6

Issue (1) : 35-43 https://doi.org/10.1007/s11709-012-0142-1

RESEARCH ARTICLE

Analysis of foundation sliding of an arch dam considering the hydromechanical behavior

Maria Luísa Braga FARINHA¹, José Vieira de LEMOS¹(

), Emanuel MARANHA DAS NEVES²

1. LNEC – National Laboratory for Civil Engineering, Av. Brasil 101, Lisboa 1700-066, Portugal; 2. IST – Instituto Superior Técnico, Av. Rovisco Pais 1, Lisboa 1049-001, Portugal

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Abstract

This paper presents the application of a methodology which can be used to assess arch dam foundation stability, using the discrete element method (DEM) and the code 3DEC. A global three-dimensional model of a dam foundation was developed, in which some discontinuities were simulated and both the grout and drainage curtains were represented. The model, calibrated taking into account recorded data, was used to carry out nonlinear mechanical analysis. The same model was employed to perform a hydraulic analysis, based on equivalent continuum concepts, which allowed the water pressure pattern within the foundation to be obtained. These water pressures were applied on discontinuities involved in the possible sliding mechanism along the dam/foundation interface, and the safety of the dam/foundation system was evaluated using a process of reduction of strength characteristics, with the aim of calculating the minimum safety factors that ensure stability. Results were compared with those obtained with the usual bi-linear uplift pressure distribution at the base of the dam, commonly used in concrete dam design. The relevance of carrying out hydraulic analysis in arch dam foundation failure studies is highlighted.

Keywords concrete dams, rock foundations, hydromechanical behavior failure analysis

Corresponding Author(s): LEMOS José Vieira de,Email:vlemos@lnec.pt

Issue Date: 05 March 2012

Cite this article:

Maria Luísa Braga FARINHA,José Vieira de LEMOS,Emanuel MARANHA DAS NEVES. Analysis of foundation sliding of an arch dam considering the hydromechanical behavior[J]. Front Struc Civil Eng, 2012, 6(1): 35-43.

URL:

https://academic.hep.com.cn/fsce/EN/10.1007/s11709-012-0142-1
https://academic.hep.com.cn/fsce/EN/Y2012/V6/I1/35

Fig.1 Downstream view of Alqueva dam

Fig.2 Geometry of the block system developed to analyze failure along the foundation joint and finite element mesh within the rock mass blocks

Fig.3 Global foundation model: cross section with simulated grout and drainage curtains (a) and detail showing the grout and drainage systems (b) (adapted from [])

Fig.4 Cross section of the global foundation model showing the location of the near-surface area of higher permeability upstream from the dam and of the horizontal layers of higher permeability

Fig.5 Calculated uplift pressures on the central cantilever

Fig.6 Recorded discharges in the foundation of each arch block located in the valley bottom and at the base of each slope and comparison with numerical results

Fig.7 Displacements at the downstream face of the dam for different friction reduction factors ( = 1.0, 1.6 and 2.0), with an operational drainage system

Fig.8 Displacements at the downstream face of the dam for different friction reduction factors ( = 1.0 and 1.6), with a non-operational drainage system

Fig.9 Variation in displacements at the top and at the base of two different blocks on the right bank, during the process of friction angle reduction, with and without drainage

Fig.10 Calculated uplift pressures with an operational drainage system and bi-linear uplift distribution along the base of the central cantilever

Fig.11 Variation in displacements at the top and at the base of two different blocks on the right bank, during the process of friction angle reduction, with different uplift distributions

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