SMALL DAMS PETITS BARRAGES

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Fig. 7.5 – Testing under way on the left-hand of the ten channels at Jackhouse Reservoir near Blackburn, UK Fig. 7.6 – One of the cable-stayed block systems remains totally intact after a water test A cross section of the dam overtopping protection with the ACB (Articulated Concrete Block) system and the downstream basin is shown in Figure 7.7. 120
Fig. 7.7 – Dam overtopping protection with the ACB system and the downstream concrete chute blocks. (Anderson and Henrich/2005) (b) Roller Compacted Concrete – RCC Roller-compacted concrete (RCC) has been used as a spillway or overtopping protection on consolidated embankments for more than 130 dams in US as pointed out by Abdo and Adaska (2007), over the past 27 years. Primary reasons for the popularity of RCC with designers and owners are simplicity, speed of construction, strength and durability, and economic advantages compared with alternative methods. The unit discharge is normally limited to a maximum of 20 m 2 /s. Comparative tests on soil-cement, RCC, and conventional concrete showed RCC to have a greater resistance than conventional concrete of higher strength, primarily because of a greater percentage of aggregate in the mixture and less paste. Several U.S. Army Corps of Engineers research projects have confirmed the excellent abrasion resistance and durability of RCC, as can be seen in the two following examples i.e. Lake Tholocco Dam and Red Rock Detention Basin Inlet Spillway. Lake Tholocco Dam (USA) Constructed in the 1930’s, Lake Tholocco Dam is an earth embankment owned by the US Army and located in Fort Rucker, Alabama, US. The dam is 732 m long with a maximum height 13,7 m, in which the service spillway is 15,2 m long reinforced concrete structure with a fixed ogee crest. A 1979 Phase Inspection Report under the National Dam Safety regulations showed that the dam did not meet current standards due to insufficient spillway capacity. Since its construction the dam’s earthen emergency spillway was operated regularly, causing severe erosion. Major storms in the 1990’s breached the emergency spillway twice. The emergency spillway failed for the second time in July 1994 during tropical Storm Alberto. After that the reservoir remained empty for six years. The USACE Mobile District investigated several upgrade alternatives and concluded that the most cost-effective solution would be to construct an RCC auxiliary spillway with a collection channel in the embankment adjacent to the reinforced concrete service spillway. 121
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SMALL DAMS Design, Surveillance and
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FOREWORD The ICOLD - International
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ACKNOWLEDGEMENT The Ad Hoc Committe
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FOREWORD ACKNOWLEDGEMENT SUMMARY TA
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5.5.5 Compaction in confined areas
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7.2.1 Introduction 7.2.2 Spillway c
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1. SMALL DAMS DEFINITION AND CLASSI
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2 Fig. 1.2 - Relationship H . V wit
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1.3 REFERENCES [1] French Committe
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2.3 ZONED EARTHFILL DAMS In arid pa
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sloping core guarantees water impou
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Fig. 2.11 - Hlinky Concrete Gravity
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Fig. 2.13 - Photograph of Neusberg
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The gabion dam as the gabion retain
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Some inflatable dams are operated b
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3.1 INTRODUCTION 3. SAFETY OF SMALL
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Condition Effect on safety 13. Dama
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Fig. 3.2 - Massive dam break overto
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and suffusion or internal instabili
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downstream part of the embankment m
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small dam impounding a lot of water
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Whenever the Supervising Authority
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emergency management organizations
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c) The decommissioning plan should
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5.1 INTRODUCTION 5. FEATURES OF THE
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5.2 DESIGN FLOODS Inadequate flood
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downstream slope will show seepage
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Fig. 5.2 - Design Freeboard 5.4.3 F
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2 U f Fe S 1400 D Where Uf is the d
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Maximum compaction is obtained at c
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characteristic must be determined.
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5.6.1 Foundation Watertightness The
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� A continuous vertical chimney d
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Thickness of pervious layer Thick D
Page 69 and 70: t 5.7.1.4 Practical Considerations
Page 71 and 72: It is generally accepted that cohes
Page 73 and 74: � Simple Bishop (1955) � Spence
Page 75 and 76: � The elements for surface draina
Page 77 and 78: The supporting layer for the rip-ra
Page 79 and 80: For very small reservoirs (fetch of
Page 81 and 82: The junction of the downstream slop
Page 83 and 84: Fig. 5.14 - Hongshiyan homogenous d
Page 85 and 86: material has been left in place or
Page 87 and 88: The homogeneous dam is recommended
Page 89 and 90: [3] OL and OH soils are not recomme
Page 91 and 92: part (core) lies in the zone (Fig.
Page 93 and 94: 6. GUIDELINES ON SURVEILLANCE OF SM
Page 95 and 96: cases the owner may retain the serv
Page 97 and 98: Surface displacement on an embankme
Page 99 and 100: Fig. 6.1 - Leakage measurement usin
Page 101 and 102: Water Level Sounder - Details of th
Page 103 and 104: pressure) Left abutment 2 5 Weir ga
Page 105 and 106: Fig. 6.9 - Recommended standpipe pi
Page 107 and 108: the others weir gauges need to be i
Page 109 and 110: � Earthquakes sensible at the dam
Page 111 and 112: APPENDIX INSPECTION CHECKLIST FOR S
Page 113 and 114: Exposed reinforcement � The condu
Page 115 and 116: These spillways can be lined or unl
Page 117 and 118: flowing water. Flowing water with h
Page 119: Fig. 7.3 - Installation of the arti
Page 123 and 124: complete construction was in 2001,
Page 125 and 126: In some cases, the downstream face
Page 127 and 128: Tube-a-manchettes injection system
Page 129 and 130: 7.3.5 Slope Protection Measures 7.3
Page 131 and 132: Pipe Rehabilitation SLIPLINING MODI
Page 133 and 134: Conditions Pros Cons Comments types
Page 135 and 136: Embankment dams that have properly
Page 137 and 138: and minimize erosion. Design of sui
Page 139 and 140: [20] SMEC- “Draft Guidelines for
Page 141 and 142: present visual information. It must
Page 143 and 144: Fig. 8.1 - Three small dams in casc
Page 145 and 146: Social Disruption low (rural area)
Page 147 and 148: Fig. 8.4 - Flood water level after
Page 149: 8.9 REFERENCES [1] BURREC (1994) -
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SMALL DAMS PETITS BARRAGES

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