Prediction of seepage from earthen dams using data mining methods

Dissertation for receiving a Master's degree in Civil Engineering

Soil and Foundation Mechanics

Shahrivar  2013 

Abstract

Dams are always considered as infrastructure structures and have vital value. In the past, the creation of dams was mainly for the purposes of providing drinking water and irrigation of agricultural fields, but today it has been developed more due to the need for hydroelectric energy and other purposes. The estimate of 20 billion cubic meters of fresh water in the world is a proof of the importance of dam construction in today's world. Therefore, checking and preventing damage to dams is of special importance. Although in the past, the overtopping phenomenon was the first reason for the destruction of dams, but today, with the increase in the period of flood design, the most important problem that has attracted the attention of engineers is the problem of seepage. Existence of seepage in earthen dams is unavoidable, but if there are suitable conditions for soil erosion, it causes washing away of susceptible points, and if necessary measures are not taken at the beginning of erosion, it will lead to the destruction of the dam. Basically, the occurrence of seepage in earthen dams is inevitable. However, seepage must be controlled so that it cannot damage the stability and safety of the dam during 50-100 years of operation of the dam. Despite all the advances made in the science of geotechnical engineering, the problem of seepage is still the main problem that occurs in dams. In this research, an attempt was made to predict seepage from the dam body by using artificial neural network as one of the most powerful and famous data mining methods. Khaki "Star Khan" be paid To achieve this goal, a data set including 1684 piezometric data was used. The data set was divided into two sections, training and validation, with a ratio of 80 to 20. The application of appropriate and practical statistical parameters showed that the presented network is well trained and has a high capability in predicting seepage phenomenon.

Comprehensive examination of dam failure statistics, various causes of earth dam failure and recognition of seepage phenomenon as the most important causes of earth dam failure are other important parts of this research.

Key words: dam construction statistics, earth dams, seepage, causes of failure. Dams, data mining, artificial neural network

Chapter 1: Overview

1-1- Introduction

The country of Iran is located on the dry belt of the planet. The average rainfall in Iran is about a third of the world's rainfall and less than a half of Asia's average rainfall. Therefore, the importance of planning and managing the use of existing water resources is considered vital. Therefore, the climatic conditions of the country and its need to build water storage structures have placed the construction of dams on the agenda of the planners, which provide the possibility of more use of river water as surface water containment structures and flood control. Controlling floods and running water with the help of building a dam is one of the infrastructure issues in the growth and development of any country, including Iran. In the past, building a dam was mainly for the purposes of providing drinking water and irrigation of agricultural fields, but today it has been developed more due to the need for hydroelectric energy and other purposes. The estimate of 20 billion cubic meters of fresh water in the world is proof of the importance of dam construction in today's world. Another important goal of dam construction is to improve and develop the irrigation and agricultural network of the downstream lands. In countries like Iran, where the temporal and spatial distribution of rainfall is inappropriate, and atmospheric rainfall occurs in seasons when there is less need for water, or most of the rainfall is concentrated in some areas, the only solution to deal with this issue is to build dams, and this is inevitable especially in countries that rely on agriculture. Dam construction brings business and national income. At the present time, irrigation networks and agricultural water supply in Iran have led to the development, improvement and economic prosperity of the regions. Another major purpose of dam construction is the use of electricity. The use of this source, which is the cheapest type of energy in most countries of the world, has different purposes depending on the needs and building characteristics.Nowadays, building a dam with the aim of producing hydroelectricity is a common thing, and advanced and even developing countries take full advantage of this existing potential.

If the construction conditions are not paid attention to and the studies are insufficient, the risk of failure threatens the dam. The statistical study of damage in damaged dams, due to the existence of similarities in the conditions, provides the possibility of providing suitable solutions in the design of dams by engineers. Damage in dams can be seen in different forms, the most common cause of dam failure, especially in recent years, is erosion due to seepage or seepage. Basically, the occurrence of seepage in earthen dams is inevitable. However, seepage must be controlled so that it cannot damage the stability and safety of the dam during 50-100 years of operation of the dam. Despite all the advances made in the science of geotechnical engineering, the seepage problem is still the main problem that occurs in dams.

1-2- Statement of the problem

Climatic conditions of the country and its need to build water storage structures have put the construction of earthen dams on the agenda of planners, which are surface water containment and flood control structures that allow more use of river water. provide According to the studies that are usually done before the construction of the dam, it is not always possible to accurately predict the hydraulic behavior of the dam body or its adjacent geological formations. Therefore, the possibility of seepage after the construction of the dam seems almost certain. The intensity of seepage is acceptable in many cases as long as the safety of the dam is not compromised. From the point of view of safety, it is important to investigate the risks caused by seepage and penetration due to the inherent complexity of their characteristics. Many reservoirs of dams built in the world have seepage. This seepage may occur from the geological formations of the construction site or the foundation of the dam or from the body of the dam. Among the consequences of poor seepage, we can mention economic issues, high hydraulic gradient that leads to phenomena such as seepage or boiling, and an increase in pore pressure that leads to a reduction in effective stress. Therefore, one of the most important points in the study stages, during the implementation operations and after the construction of earthen dams, is the issue of seepage from the foundation and body of the dam, which has been a problem facing the designers of the dams. Therefore, it is necessary to accurately calculate the amount of seepage from the body and foundation of the dam and to examine the methods of controlling or reducing it, technically and economically, in order to prevent life and financial risks. Accurate estimation of the seepage from the body of earthen dams is an important challenge in the design of these huge structures. The use of instrumentation may provide an accurate estimate of this phenomenon to some extent, but the upcoming problems such as the failure of the instruments due to time, expenditure of money and manpower for reading, etc., have made this method difficult. It is common to use analytical solution methods proposed by different researchers to evaluate the amount of seepage from the body of earthen dams located on impermeable bed due to their ease of use. However, these analytical methods use assumptions to simplify the construction of equations, which may lead to large errors. Therefore, according to the contents stated in the previous sections, the aim of this study is to provide an artificial neural network model [1] to more accurately predict the amount of seepage from the body of earthen dams and eliminate the above problems. Therefore, it is tried to predict the seepage phenomenon in earthen dams based on the data of a particular dam's instruments and the use of data mining methods. 1-3- The importance and necessity of the research Iran is located on the dry belt of the earth. The average rainfall in Iran is about a third of the world's rainfall and less than a half of Asia's average rainfall. Therefore, the importance of planning and managing the use of existing water resources is considered vital. Therefore, the climatic conditions of the country and its need to build water storage structures have placed the construction of dams on the agenda of the planners, which provide the possibility of more use of river water as surface water containment structures and flood control. Controlling floods and running water with the help of building a dam is one of the infrastructure issues in the growth and development of any country, including Iran. In the past, building a dam was mainly for the purposes of providing drinking water and irrigation of agricultural fields, but today it has been developed more due to the need for hydroelectric energy and other purposes.