SMALL DAMS PETITS BARRAGES

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Fig. 6.3 – Vegetation debris upstream the weir gauge. Uplift and Pore Water Pressure It is important to check the position of the water table and how pore pressures are evolving in the foundation and in the embankment itself. Measurement devices can be classified in two types: Standpipe piezometers with a length of slotted tube from a few decimeters to several meters (Fig. 6.4); Fig. 6.4 – Standpipe piezometer installed in a borehole. The open tube piezometers is cheap and easy to read and allows anomalies to be detected in the foundation (by revealing insufficient pressure drop), or in the downstream slope (problems of saturation). Given the response time, the open tube piezometer is more suitable for permeable ground, usually with permeability coefficient K ≥ 10 -5 cm/s. 100
Water Level Sounder - Details of the water level sounder are shown on Fig. 6.5 and 6.6. This device is comprised of a suitable length of ¼ inch coaxial cable or tape, fitted at the ends to contact the water surface in the plastic riser tube and for connection to an ohmmeter. Fig. 6.5 – Water level sounder for standpipe piezometers. Pore pressure cells give precise localized measurement and offer faster response times than standpipe piezometers. Fig. 6.6 – Different models of vibrating wire piezometers. The vibrating wire piezometers has usually a thick-wallet stainless steel housing to prevent the vibrating wire transducer from responding to total stresses acting on the housing, a very robust and water-blocked signal cable, heavy-duty seals, and long high air entry filters. They are good instruments to measure the pore water pressures at the foundation or at the earth embankment with permeability coefficient equal or lower than 10 -6 cm/s, for long-term survivability, usually about 30 years. Displacement Measurement Measurement of the absolute displacements of the dam’s survey targets with respect to fixed benchmarks (Fig. 6.7) set up in zones that are not likely to be affected by any significant movement; altimetric measurements (settlement) and planimetric measurements (upstream- 101
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SMALL DAMS Design, Surveillance and
Page 3 and 4:
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
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 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: Fig. 6.1 - Leakage measurement usin
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
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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