CREATESPACE Physical modeling of PIANO KEY weir: Detailed experimental study

Dams are major hydraulic structures regarding water control, therefore they have essential role in developing our civilization. Huge quantities of water are stored by dams in large reservoirs. Dam safety is threatened by increasing intensity and frequency of floods in the recent years. This issue requires development of improved spillway structures in order to avoid overtopping and failure of dams. As a consequence, dam engineering is progressing toward the concept of “labyrinth weir” due to its simplicity and very high hydraulic performance. Labyrinth structure is composed of vertical wall built on flat floor in a repetitive non-linear layout. Using this weir as spillway can satisfy large discharge requirements during flood events, and maintain large reservoir storage under normal flow conditions. From the economic point of view, the cost of labyrinth weirs is less than that of gated spillways in terms of both construction and maintenance. However, because of the large base area taken by the labyrinth layout which is not found on typical gravity dam sections, use of this weir is very limited in dams. Therefore, an improved version of labyrinth weir has been developed in the last decade as alternative to the traditional one. This solution was given the name Piano Key Weir as its repetitive layout is similar to the keys of piano. The base area of this weir has been reduced making it the favourable solution for dam rehabilitation and new dam projects. This book is the result of a comprehensive parametric study which was held as partial fulfillment of master’s degree in the University of Kufa (Iraq). The study is based on laboratory experiments which aim to determine the Piano Key Weir discharge coefficient for different geometrical configurations under free and submerged flow conditions. Eight geometrical parameters were tested using 26 models in an experimental flume. The book is divided into three parts, namely “Fundamentals”, “Physical Modeling”, and “Results and Discussion”. Part one “Fundamentals” contains two chapters and it is devoted to basic concepts, introductory ideas (Chapter 1) and literature review about the discharge capacity of Piano Key Weir (Chapter 2). Part two “Physical Modeling” describes the preparation and execution of experimental work. Functional relations of the parametric study have been developed in (Chapter 3) by dimensional analysis technique. (Chapter 4) presents the details of laboratory work including flume description, flow calibration, manufacturing of models and testing procedures. Finally, Part three “Results and Discussion” demonstrates the analysis and formulation of experimental results. (Chapter 5) discusses the visual observations during experiments and flow behavior in different conditions. Then, analysis of results for each physical model is presented in (Chapter 6) including free and submerged flow conditions. These results are then formulated in (Chapter 7) using statistical software to develop formulae that predict the values of discharge coefficient in different conditions. Correspondingly, additional resources are provided in the appendices of this book. Tables of data sets for the entire experimental work are given in (Appendix A). Comprehensive collection of illustrative photographs during various stages of testing is presented in (Appendix B), whereas (Appendix C) contains detailed drawings for all experimental models.