please get me seminar report on piano key wiers

seminar report on piano key spillways for dams

Similar to labyrinth weirs, piano key (PK) weirs are folded in plan to increase discharge capacity for a given spillway channel width. Because of their configuration, PK weirs may be better suited than labyrinth weirs for applications where the weir footprint (length and/or width) dimensions are restricted (e.g., crest of gravity dams) as PK weirs can facilitate a significant amount of weir length relative to their footprint size. For channel applications without significant footprint restrictions, labyrinth and PK weirs may both represent viable spillway options. This paper provides an overview of some of the advantages and disadvantages of PK weirs, labyrinth weirs, and gated structures in channel applications and/or dam rehabilitation, including economic, structural, and hydraulic considerations. Two case studies are reviewed where a labyrinth weir or other type of control structure were constructed. The potential application of a PK weir was comparatively assessed for the same projects, had the option been available at the time of design. Free-flow spillways are simpler and saferthan gated ones, but the low specific flow of their traditional shapes requires high spilling nappe depths and thus huge losses of storage (100 x 109 m3 worldwide). A newly evolved shape of free-flow spillway (the "Piano Key weir") has the potential to increase the specific flow as high as fourfold at lower discharges. It could substantially increase, at low cost, the safety and the storage and/or the flood control efficiency of many existing as well as new dams. It is thus very advantageous to increase thespecific flow as much as possible. Some tens of existing spillways have been designed accordingly as vertical walls on a flat bottom, with a trapezoidal labyrinth layout which is much longer than the spillway length (often four times). They usually double the specific flow of an Ogee Spillway. Piano-Key Weir derives its name from its plan-form shape which looks like a ‘piano-key’. It is configured as polygonal walls such as to provide a much longer crest length than the conventional ogee spillways.