DESIGN MANUAL FOR RCC SPILLWAYS AND OVERTOPPING PROTECTION Prepared by URS Greiner Woodward Clyde PORTLAND CEMENT ASSOCIATION Published by: Portland Cement Association 5420 Old Orchard Road Skokie, Illinois 60077-1083 USA Phone: 847.966.6200 Fax: 847.966.9781 Internet: www.portcement.org Print history: First edition 2002 © 2002 Portland Cement Association All rights reserved. No part of this publication may be repro- duced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the copyright owner. Printed in United States of America This publication is intended SOLELY for use by PROFES- SIONAL PERSONNEL who are competent to evaluate the significance and limitations of the information provided herein, and who will accept total responsibility for the application of this information. The Portland Cement Asso- ciation DISCLAIMS any and all RESPONSIBILITY and LIABILITY for the accuracy of and the application of the information contained in this publication to the full extent permitted by the law. Cover photos Upper left: Kerrville Dam, Texas Bottom: Blue Diamond Dam, Nevada. DESIGN MANUAL FOR RCC SPILLWAYS AND OVERTOPPING PROTECTION PORTLAND CEMENT ASSOCIATION iv Table of Contents Table of Contents Chapter Page No. 1 RCC SPILLWAYS AND OVERTOPPING PROTECTION . 1 1.0 Background . 1 2 OPERATIONAL REQUIREMENTS AND SPILLWAY LOCATION . 9 2.1 General . 9 2.2 Operation Frequency and Spillway Location . 9 2.3 Dam Stability and Downstream Erosion . 11 3 INVESTIGATION. 13 3.1 General . 13 3.2 Desk Study and Site Reconnaissance . 13 3.3 Subsurface Investigation . 13 3.4 RCC Aggregate Investigations. 16 4 SLOPE STABILITY AND FOUNDATION ANALYSIS . 17 4.1 General . 17 4.2 Slope Stability . 17 4.3 Foundation Analysis. 18 5 SEEPAGE ANALYSIS. 21 5.1 Seepage Considerations . 21 5.2 Steady-State Seepage Analysis. 24 5.3 Analysis of Uplift Pressures. 25 5.4 Analysis of Filter Compatibility . 26 6 OVERTOPPING SPILLWAY DESIGN . 29 6.1 Introduction . 29 6.2 Spillway Location . 29 6.3 Hydraulics of Stepped Spillways . 30 6.4 Spillway Channel . 30 6.5 Width of the Overtopping Protection . 34 6.6 Crest and Control Structures . 35 6.7 Approach Apron Slab . 37 6.8 Downstream Apron Slab . 38 6.9 Cut-off Walls . 39 v Design Manual for RCC Spillways and Overtopping Protection • EB218 Chapter Page No. 6.10 Joints for RCC Spillway Slab . 40 6.11 Drain Outlets . 43 6.12 Training Walls and Abutment Protection . 44 6.13 Soil Cover for RCC Spillways . 46 7 RCC MIX DESIGN . 47 7.1 General . 47 7.2 Soil Compaction Method of Mix Design . 48 7.3 Conventional Concrete Method of Mix Design . 51 8 INSTRUMENTATION AND MONITORING . 53 9 CONSTRUCTION CONSIDERATIONS . 55 9.1 Construction Access/Site Layout . 55 9.2 Dewatering and Foundation Preparation. 56 9.3 RCC Production . 57 9.4 RCC Delivery/Transport Systems. 57 9.5 Spreading of RCC . 59 9.6 Compaction of RCC . 60 9.7 Curing of RCC and Effects of Climate . ..