Risk analysis on the fill dam safety : Ataturk Dam case study

Water is a life source without alternative for creatures living on earth. Creatures have developed projects for the optimal use of water due to several purposes in order to make use of water. One of these projects is dams. While aspects such as detailed project designing, error-free production and optimal operating conditions have utmost importance in construction of dams, determination of risks that may arise during production or operation of the structure and taking required measures against such risks are not less significant. Within this context, anticipating the risk groups, requiring improvement to prevent dam accidents experienced in the past and aiming to protect the life in the surrounding in addition to the structure, dam safety issue has gained importance in the recent years. In addition to available dams, dam safety concerns subjects such as project design, production, operation and maintenance of dams to be constructed. Today, attaining a legal and technical infrastructure in many developed countries, the issue of dam safety is being advancing gradually every other day in our country through universities, associations, congresses and administrative mechanisms. Addressing dam safety, within scope of this study, In the Chapter 1, dam safety and the required importance for the risks affecting the dams are explained. Mankind's need for water throughout the history is emphasized and the need for building dams for this requirement is stated. Dams in the world and in Turkey are addressed. It is also stated that the current conditions require economic use of water. It is explained that safety of the dams is a very important issue both in the national and international level. Despite this, while the current situation clearly shows the hazards, it is reminded that only a few countries have a fully equipped dam safety program. In the last part of the chapter, the roadmap of the study is stated. In the Chapter 2, the concepts of hazard and safety are explained. It is stated that despite the technological advancement, natural disaster still pose a threat for humanity. It was explained that the big constructions like dams may pose not only known hazards, but also unusual hazards. Land solution procedures in relation to the concept of hazard are listed. The importance of the concept of safety in engineering, which is defined as the case not posing hazard, is emphasized. Hazard and safety are discussed along with the risk factor, and displayed in a chart. Additionally, topics regarding the risks posed in the dams are mentioned. These topics are discussed in the framework of safety. The other professions effective in addition to construction engineering are stated in terms of dam safety. 3 ways, through which the dam safety is monitored in different disciplines, are given. These 3 ways are respectively prevention, control and decreasing. Stability of the dams providing the society with such advantages as energy, irrigation water, flood control and recreation, is examined. It is highlighted that while trial and error method has been common in the first years of dam construction, now research and development is important. It is underlined that the dams, which are built more and more making use of the technology, are now constructed on less suitable spots. It is stated that because the dams directly affect security of life and property both during their construction and operation, risk calculations have to be made more carefully and meticulously and should be frequently checked. The last part of the chapter is spared for the reasons and factors of the insufficiencies in the dams. It is stated that the most effective issue in dam destruction is insufficiency. Structural destruction and performance destruction are discussed and it is stated that the dams are designed according to the concept of structural destruction. Factors creating the insufficiency are listed and explained with examples. In this context, examples of the dam accidents that arose due to the insufficiencies and lead to loss of life and property are given. In the Chapter 3, the subject of examining current dams and measurement tools in the fill dams are analyzed. Examination issues are stated and the importance of particularly the dam body is highlighted. Importance of anticipations in examination is stated. Concept of examination is divided into types and separate principles are explained. The second part of the chapter is on measurement and measurement equipment. It is stated that through dam measurement devices, equipment are placed on the dam body or its several spots and it is possible to monitor dam's actions in time. In this context, dam measurement devices are listed and explained. Forms of the relevant equipment used in the worksite in fill dam construction are explained in figures. After that, the assessment and analysis procedures required as a result of the examinations and measurements are emphasized. In the Chapter 4, the concept of risk is addressed and importance of risk in engineering is discussed. After explaining the concept of risk, possible risks to be encountered in the construction industry are stated. Risks in the construction industry are listed and measures to be taken against these risks are explained. Controllable and uncontrollable risks are explained and their dependence on the design, workmanship standard and quality of the used material is analyzed. Complete and partial dependence of the risks in the construction sector are emphasized. The terms of static risk and speculative risk are explained. It is stated that the construction projects host several uncertainties arising from various factors. It is discussed that at this point, risk analysis is an essential fact. It is also stated that risk analysis has become compulsory for some projects and this type of projects are listed. The basic issue in risk analysis is that risk estimates have to be conducted realistically and the results have to be correctly interpreted and expressed concretely with a realistic approach. The last part of the chapter is spared for determining the risk groups for the dams. In this part, a risk potential classification table for the dams is given. Within the framework of the regarding table, dams have to be assigned risk points depending on their qualities and the area they affect. It is explained that as a result of the related points, risk class of the dams is revealed. In the Chapter 5, Atatürk Dam, which is the largest dam in Turkey, is introduced with its importance. The geodesic deformation measurement procedures for Atatürk Dam are explained. It is stated that the horizontal and vertical measurements are made with the classical or satellite based measurements conducted periodically on the deformation networks created for this purpose. Geodesic and non-geodesic measurements, as well as the tools used in these measurements are explained. It is stated that several deformation points are placed on the dam body and the regions to create movement with these points are selected. It is explained that the deformation network is created as a result of the relevant regions. Perpendicular movements arising as a result of the deformation network are given in table. Kriging method for calculating the perpendicular movements arising as a result of the deformation networks is explained in detail. Explanation of Kriging method is supported with an example. Via Surfer_10 software, perpendicular movements on Atatürk Dam are modeled with Kriging method. Coordinates and perpendicular movements in the deformation network are taken as basis in modeling. With the interpolation-based Kringing method, data on the dam body are obtained. Variation diagram of the created model is drawn. Efficiency of the model is calculated under a separate title. Values of the created model are compared with the data obtained from 15th Regional Directorate of State Hydraulic Works. The difference arisen as a result of the assessment is explained and the required calculations are conducted. While making the calculations, a part is taken from the section of the dam posing risk on the dam crest. Then, 174-month sitting graph is obtained for this section. 5-year data from this graph is selected according to the model's period and analyzed. As a result, it is determined that the calculation provides 90.71% of reliability. In the Chapter 6, it is emphasized that as the dams are huge constructions, their designs have to be made very carefully and meticulously. It is stated that many people lose their lives due to dam destructions and serious damages occur. It was highlighted that for safe operation of the dams, they have to be monitored periodically throughout their lives. In the last part of the section, the model created as a result of this study is analyzed. Sinking on Atatürk Dam's body that arose between May 2006 and December 2011 are assessed. Model's efficiency is emphasized.