Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

During planning for dam projects, good practice usually calls for appropriate investigations to help assure the development is not located on or immediately adjacent to active faults. There are examples of projects, however, where an active fault has been discovered in or close to a dam foundation and engineering solutions have been incorporated into design to enable satisfactory performance of the dam should fault displacement occur during project operation. In some cases, the existence of such hazards only becomes evident late in the design cycle when the dam site is considered fixed and hazard avoidance is not an easy option. The 960-MW Neelum-Jhelum Hydroelectric Project in Pakistan is being constructed within a geologically complex and seismo-tectonically active setting. During feasibility studies, a major thrust fault at the dam site was deemed inactive. However, during detailed design and after commitment to start construction with international contractors, the potentially active nature of the fault came to be understood. The dam is re-designed as a composite structure, with a zoned fill section overlying the fault and the remainder of the dam consisting of a concrete gravity feature with integral gated spillway. The fill section designed to accommodate the maximum amount of offset that could occur on the fault below. This concept has been adopted on other projects elsewhere, such as the approach dams leading to the new Pacific Locks Complex, which are intersected by segments of the active Pedro Miguel fault for the new Third Set of Locks of the Panama Canal. During construction of the Neelum-Jhelum dam, the actual fault trace was found unfortunately to be not entirely beneath the fill section and that some of the concrete super-structure would overlie the fault. Innovative subsurface foundation treatments have been developed to help direct any potential future fault movement into the fill and away from the concrete part of the dam. This paper describes these measures and the analytical methods used in design development.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Design Details to Accommodate Fault Movement in a Dam Foundation

Chicago, Illinois

During planning for dam projects, good practice usually calls for appropriate investigations to help assure the development is not located on or immediately adjacent to active faults. There are examples of projects, however, where an active fault has been discovered in or close to a dam foundation and engineering solutions have been incorporated into design to enable satisfactory performance of the dam should fault displacement occur during project operation. In some cases, the existence of such hazards only becomes evident late in the design cycle when the dam site is considered fixed and hazard avoidance is not an easy option. The 960-MW Neelum-Jhelum Hydroelectric Project in Pakistan is being constructed within a geologically complex and seismo-tectonically active setting. During feasibility studies, a major thrust fault at the dam site was deemed inactive. However, during detailed design and after commitment to start construction with international contractors, the potentially active nature of the fault came to be understood. The dam is re-designed as a composite structure, with a zoned fill section overlying the fault and the remainder of the dam consisting of a concrete gravity feature with integral gated spillway. The fill section designed to accommodate the maximum amount of offset that could occur on the fault below. This concept has been adopted on other projects elsewhere, such as the approach dams leading to the new Pacific Locks Complex, which are intersected by segments of the active Pedro Miguel fault for the new Third Set of Locks of the Panama Canal. During construction of the Neelum-Jhelum dam, the actual fault trace was found unfortunately to be not entirely beneath the fill section and that some of the concrete super-structure would overlie the fault. Innovative subsurface foundation treatments have been developed to help direct any potential future fault movement into the fill and away from the concrete part of the dam. This paper describes these measures and the analytical methods used in design development.