SMALL DAMS PETITS BARRAGES

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Fig. 5.16 – Size range of impervious cores used in zoned embankments. Table 5.22 – Recommended slope for small homogeneous earthfill dams on stable foundations.[3] Type Subject to rapid drawdown [1] Soil Classification [2] Upstream slope Downstream slope Homogeneous or modified - homogeneous No GW, GP,SW, SP GC, GM, SC, SM CL, ML CH, MH Pervious, unsuitable 2.5:1 2:1 3:1 2.5:1 3.5:1 2.5:1 GW, GP,SW, SP Pervious, unsuitable Modified homogeneous - Yes GC, GM, SC, SM CL, ML 3:1 3.5:1 2:1 2.5:1 CH, MH 4:1 2.5:1 [1] Drawdown rates of 15cm or more per day after prolonged storage at a high reservoir levels. [2] OL and OH soils are not recommended for major portions of homogeneous earthfill dams. PT soils are unsuitable. Type Table 5.23 – Recommended slopes for small zoned earthfill dams on stable foundation.[3] Zoned with minimum core A [1] Zoned with maximum core [1] Zoned with maximum core [1] levels. Subject to rapid drawdown [2] Not critical [4] No Yes Shell Material Classification Rockfill, GW, GP, SW (gravelly), or SP (gravelly) Rockfill, GW, GP, SW (gravelly), or SP (gravelly) Rockfill, GW, GP, SW (gravelly), or SP (gravelly) Core Material Classification [3] GC, GM, SC, SM, CL, ML, CH, or MH Upstream slope 2:1 2:1 Downstream slope GC, GM 2:1 2:1 SC, SM 2.25:1 2.25:1 CL, ML 2.5:1 2.5:1 CH, MH 3:1 3:1 GC, GM 2.5:1 2:1 SC, SM 2.5:1 2.25:1 CL, ML 3:1 2.5:1 CH, MH 3.5:1 3:1 [1] Minimum and maximum size cores are as shown on Figure 3. [2] Rapid Drawdown is 15cm or more per day after prolonged storage at a high reservoir 88
[3] OL and OH soils are not recommended for major portions of the cores of earthfill dams. PT soils are unsuitable. [4] Rapid drawdown will not affect the upstream slope of a zoned embankment that has a large upstream pervious shell. 3. Experience of Australia For homogenous dams the following batter slopes are recommended for embankments built of soils classified according to the Unified Soil Classification system Table 5.24 – Batter slope with soil classification and height.[4] Case type A B Homogenous or Modified Modified homogenous Purpose Detention or storage Storage Subject to rapid drawdown No Yes GW GC CL CH GW GC CL CH Soil GP GM ML MH GP GM ML MH classification SW SC SW SC SP SM SP SM Dam Height (m) & Slope 0 - 3 U/S P 2.5:1 2.5:1 3.5:1 P 3:1 3.5:1 4:1 D/S 2:1 2:1 2.5:1 2:1 2.5:1 2.5:1 3 - 7 U/S P 2.5:1 3:1 3:1 P 3.5:1 4:1 4:1 D/S 2.5:1 2.5:1 3:1 2.5:1 3:1 3:1 7 - 10 U/S P 3:1 3:1 3.5:1 P 3.5:1 4:1 4:1 D/S 3:1 3:1 3:1 3:1 3.5:1 3.5:1 Notes: U/S = upstream slope and D/S = downstream slope Rapid drawdown rates of 1.0 m/day. “P” = pervious denotes soils which are not suitable. 4. Experience of Japan The cross section shape of the dam shall be determined in accordance with calculations to ensure its stability. The standard cross section diagram shown in Figure 5.17 and Table 5.25 shall be used in determining the cross section shape of the dam. The thickness of the paved portion is not to be included in the height of the dam when the top of the dam is used as a road. H2 H 1 F HWL 1: n Foundation layer FWL h 1 b nF 1 3 F Impervious core d3 d2 n F n 1: n 1 1: n 11: n h 4 2 h 2 1: n 3 n 3 d 4 d 1 B h 3 H 1: n 4 89
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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
Page 37 and 38: and suffusion or internal instabili
Page 39 and 40: downstream part of the embankment m
Page 41 and 42: small dam impounding a lot of water
Page 43 and 44: Whenever the Supervising Authority
Page 45 and 46: emergency management organizations
Page 47 and 48: c) The decommissioning plan should
Page 49 and 50: 5.1 INTRODUCTION 5. FEATURES OF THE
Page 51 and 52: 5.2 DESIGN FLOODS Inadequate flood
Page 53 and 54: downstream slope will show seepage
Page 55 and 56: Fig. 5.2 - Design Freeboard 5.4.3 F
Page 57 and 58: 2 U f Fe S 1400 D Where Uf is the d
Page 59 and 60: Maximum compaction is obtained at c
Page 61 and 62: characteristic must be determined.
Page 63 and 64: 5.6.1 Foundation Watertightness The
Page 65 and 66: � A continuous vertical chimney d
Page 67 and 68: 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: The homogeneous dam is recommended
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 and 120: Fig. 7.3 - Installation of the arti
Page 121 and 122: Fig. 7.7 - Dam overtopping protecti
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
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[20] SMEC- “Draft Guidelines for
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present visual information. It must
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Fig. 8.1 - Three small dams in casc
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Social Disruption low (rural area)
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Fig. 8.4 - Flood water level after
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8.9 REFERENCES [1] BURREC (1994) -
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SMALL DAMS PETITS BARRAGES

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