Arch Dams: Designing and Monitoring for Safety

402 Pages·1999·26.06 MB·English

by  José O. Pedro (eds.)

CISM COURSES AND LECTURES
Series Editors:
The Rectors of CISM
Sandor Kaliszky- Budapest
Mahir Sayir - Zurich
Wilhelm Schneider -Wien
The Secretary General of CISM
Giovanni Bianchi -Milan
Executive Editor
Carlo Tasso -Udine
The series presents lecture notes, monographs, edited works and
proceedings in the field of Mechanics, Engineering, Computer Science
and Applied Mathematics.
Purpose of the series is to make known in the international scientific
and technical community results obtained in some of the activities
organized by CISM, the International Centre for Mechanical Sciences.
INTERNATIONAL CENTRE FOR MECHANICAL SCIENCES
COURSES AND LECTURES -No. 367
ARCH DAMS
DESIGNING AND MONITORING FOR SAFETY
EDITED BY
JOSE 0. PEDRO
NATIONAL LABORATORY OF CIVIL ENGINEERING
~ Springer-Verlag Wien GmbH
This volume contains 153 illustrations
This work is subject to copyright.
Ali rights are reserved,
whether the whole or part of the material is concemed
specifically those of translation, reprinting, re-use of illustrations,
broadcasting, reproduction by photocopying machine
or similar means, and storage in data banks.
© 1999 by Springer-Verlag Wien
Originally published by Springer-Verlag Wien New York in 1999
SPIN 10730576
In order to make this volume available as economically and as
rapidly as possible the authors' typescripts have been
reproduced in their original forms. This method unfortunately
has its typographical limitations but it is hoped that they in no
way distract the reader.
ISBN 978-3-211-83149-6 ISBN 978-3-7091-2488-8 (eBook)
DOI 10.1007/978-3-7091-2488-8
PREFACE
Arch dams are in genera/large structures integrated in hy'draulic projects
of social and economical significance and impact on the environment, their
safety and performance being therefore of the utmost importance. The
assessment of safety and performance of arch dams, either for design of new
dams or for monitoring of the existing ones, requires the utilisation of
appropriate criteria, models and methods of analysis.
A short course on Mathematical modelling for arch dam design and
safety evaluation, was held in Udine (Italy) in the week 4-8 of September, I 995.
This course was organised by the International Centre for Mechanical Sciences
(Udine) in co-operation with the National Laboratory of Civil Engineering
(Lisbon, Portugal), and provided a comprehensive understanding of the modern
criteria, models and mathematical methods of analysis of arch dams. It was
developed in thirty lectures dealing with the following Jive themes: models and
methods of analysis, scenarios for the construction phase, scenarios for the
operation conditions, dynamic behaviour, and safety and performance of arch
dams. These themes were developed respectively by Professors M. Fanelli
(National Power Board, Italy), W. Wittke (Technical University of Aachen,
Germany), G. Heigerth (University of Technology of Graz, Austria), R.T.
Severn (University of Bristol, United Kingdom), and myself The course was
attended by twenty four post-graduate students and professionals from
Universities, Research Institutions and Consultant Firms of the following
countries: Austria, Bulgaria, Canada, Germany, India, Iran, Italy, Poland,
Portugal, Spain, Sweden, Switzerland and United Kingdom.
Since the publication of the lectures of the course was considered of interest, the
present volume was prepared. It is entitled Arch dams: designing and monitoring
for safety, and is broken down into three parts: Part 1 -Safety and performance
of arch dams; Part 2 -Models and me/hods of analysis; Part 3 -Dynamic
behaviour of arch dams. Unfortunately, it has not been possible to obtain the
texts of the lectures concerning the other two themes.
Part 1 presents a brief characterisation of arch dams in the world, and a
historical background of these structures since the Roman times up to our days.
The basic concepts of safety and performance, and the criteria, models and
methods of analysis used for their evaluation are discussed and illustrated using
examples. Reference is made to the legal aspects concerning the safety of dams.
Part 2 develops a detailed and thorough explanation of the models and
mathematical methods of analysis of arch dams. The simple approaches for
preliminary designs, as well as the state-of-the-art finite element approaches are
discussed, both for static and dynamic loads, and are illustrated by examples.
Part 3 deals with the dynamic behaviour of arch dams, especially under
seismic actions. A comprehensive presentation is made concerning the definition
of the design seismic actions, the dam-reservoir interaction, the model analysis,
and the full scale dynamic tests. Examples are given for dams all over the world.
Thanks are due to the International Centre for Mechanical Sciences and
the National Laboratory of Civil Engineering for their support to the course on
arch dams and to the present publication. Special acknowledgements are due to
Professors M. Fanelli and R.T. Severn for having participated in the course and
in the preparation of this volume, as well as to Professors W. Wittke and G.
Heigerth for their participation in the course. Nuno Grossmann, Research
Officer of the National Laboratory of Civil Engineering, deserves also our
gratitude for his contribution in the preparation of Part 1 of the present volume.
Jose Oliveira Pedro
CONTENTS
Page
Preface
Part 1 - Safety and Performance of Arch Dams
by J.O. Pedro.. .. .......... ·n······· .... ·······n······ ·n····· ......... ·n············ ...... .. .... l
1. Introduction ....... n·············. ..... .. ..... n ...... . ... n ..... . .... .. .... 3
2. Arch Dams. Historical Background...... . ...... ............... . ............ n............... .. ... 7
3. Safety and Performance of Arch Dams ............................................................................ ·n······ 27
4. Evaluation of Safety and Performance of Arch Dams ..... nn·················· ·n····· 43
5. Legal Aspects Concerning Dam Safety....... . ··n······························· ·n····· 65
6. References •n••······ •n···· ········ . n•••········· .. ·······•·••n•••••·• ... ········ on•···· 69
Part 2 - Models and Methods of Analysis
by M. Fanelli.... .. ·····n········· ... ··n························· ···n············· .... 79
1. Generalities and Critical Considerations ............................... nn. .... . .. n . . ..... 81
2. Analysis & Back Analysis: Different Models & Methods........ .. .... 105
3. The Finite Element Method of Analysis ........ n......................... ............... . ..... 163
4. Bibliographic List .. .. .... n . n. .. .... n. .......... ..... .... 277
5. AppendiX ...... ····••n••····· .... ••n ............. n.. •••n••••·········· •n•································· .............. 279
Part 3 - Dynamic Behaviour of Arch Dams
by R. T. Severn n···· . . . . . n . . ....n .. . ....... .. . ...... n. ...... ...... 289
1. Estimation of Earthquake Ground Motion for Arch Dam Design .......... 291
2. Reservoir Induced Seismicity (RIS) nOn . ..... . . ....... ······· 307
3. Dam Reservoir Interaction ...... on• ........ . ••n••··· ............ ••••nn•• •••nnO 311
4. Model Studies for Earthquake Loading .n .................... n .... non 339
5. Full-Scale Dynamic Testing and Mathematical Validation..... 359
n ••
6. Differential Ground Motions ... 389
n •••••••••••••••••••• n •• • ••••••••••••••••••••••••••••••••••••••••••••••
PARTl
SAFETY AND PERFORMANCE
OF ARCH DAMS
by
J. 0 Pedro
National Laboratory of Civil Engineering, LNEC
Portugal
1
INTRODUCTION
1 - The supply of fresh water is a matter of great concern for a farseeing water management
because fresh water is a finite and limited resource (it corresponds to only 2% of all the water
existing in the world). The demand for it increases rapidly, in accordance with the increase of
the world population. An adequate management of the fresh water resources is therefore
necessary, and the management of the river water resources, which form only a small part of
the total fresh water resources, is particularly important for a sustained development.
In general, the river water management projects (whenever possible multi-purpose
projects for water supply, irrigation, power production, navigation, flood control and
recreation) require the construction of dams. A dam project includes several components, such
as:
-the dam body and its foundation;
- the appurtenant works, which are necessary either for the operation (intake towers,
channels, power station and associated hydraulic circuits, penstocks, tunnels and other
underground works, protection devices and restitution circuits, navigation and fish locks,
hydraulic and electromechanical equipment, logways) or for the safety (spillways, surface and
bottom outlets, energy dissipaters - stilling basins, roller buckets or plunge pools - hydraulic
and electromechanical equipment);
-the reservoir and the slopes downstream of the dam.
4 1.0. Pedro
The problems of the projects for large dam have been considered within the
frame of the International Commission on Large Dams (!COLD). According to !COLD, large
dmns are those which are:
-above 15m in height (measured from the lowest point of the foundation to the top);
or
- between 10 m and 15 m in height and meet at least one of the following conditions:
1) the crest length is not less than 500 m; 2) the capacity of the reservoir is not less than 1( )6
m3; 3) the maximum flood discharge is not less than 2,000 m3/s; 4) it has specially difficult
foundations; 5) it is of an unusual design.
Dams may be built with different materials and may have different characteristics. They
are usually classified as follows:
-concrete and masonry dams (gravity, buttress, arch and multiple arch types);
-earth.fill and rockfill structures.
The present course deals with arch dams only; we shall also refer to multiple arch dams,
particularly to large-span multiple arch dams.
2 - An arch dam is a concrete or masonry structure curved in plan, so as to transmit the major
part of the water load to the abutments.
Arch dams may be classified into the two following groups:
-arch-gravity dams, in general, thick vaults, with a single curvature in plan;
- double curvature arch dams, in general, thin shells or domes, with a vertical and
horizontal curvature.
As mentioned above, we shall also consider the single or double curvature arches
included in multiple arch dams.
The main terminology used for arch dams is summarised in Fig.1.
The choice of an arch structure as a suitable design solution for a dam project may be
affected by different factors, particularly by geotechnique, topography, hydrology and climate.
The existence of rock abutments is a condition of vital importance. Both U or V shaped
valleys may be appropriate for arch dams, provided the span/height ratio is not very large.