**1. Introduction**

80 Multivariate Analysis in Management, Engineering and the Sciences

203-245, 1997.

Weiss K D. Paint and Coatings: a mature industry in transition. Prog. Polym. Sci, v. 22, p.

The monitoring of a dam structure can generate an enormous mass of data of which the analysis and interpretation are not always trivial. It is important to select the information that better "explain" the behavior of the dam, making possible the prediction and resolution of eventual problems that may occur.

The world largest hydroelectricity generator, Itaipu hydroelectric power plant, has more than 2.200 instruments that monitor its geotechnical and structural behavior, and these instruments have readings stored on a database for over 30 years. The high dimensionality and the large quantity of records stored on the databases are nontrivial problems that are kept so that one can pursue "knowledge" through these data.

The detailed analysis of the auscultation instrumental data requires a combination of knowledge of Engineering, Mathematics and Statistics, as well as the previous experience of the engineer or the technician responsible for the analysis of these data. That consumes a lot of time, and often makes it impossible to accomplish this task in an efficient way. This is the reason why the use of techniques and computational instrumentation to help the decisions maker is extremely important.

There are no records of the existence of methods that perform the classification of monitoring instruments in dams. In case of reading intensification this hierarchy could be useful to define which instrument to chose.

© 2012 Villwock et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Villwock et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The aim of this paper is to identify the tools that are the most significant for the analysis of a dam behavior, which maximizes the effectiveness and efficiency of the analysis of the readings. It shows a methodology based on the field of Multivariate Analysis, applied to the Hierarchical Cluster Analysis in order to identify the groups of instruments similar to Ward's linkage method. The factor analysis of the strain gauge of each instrument group was also applied, performing the hierarchical cluster of monitoring instruments in dams, detecting the main instruments.

Itaipu Hydroelectric Power Plant Structural Geotechnical Instrumentation

Temporal Data Under the Application of Multivariate Analysis – Grouping and Ranking Techniques 83

In [5] show a table which contains the estimative for the most common causes of ruptures on dams. Among them, the following are highlighted: problems of the foundation; inappropriate spillway; structural problem; different declinations; extreme low-pressure; rupture of landfills; defective materials; incorrect operation; actions of war, and earthquakes. All these problems can be diagnosed with the monitoring of the dam instrumentation, with exception of the last two ones, which percentage of frequencies sum

According to [6], the global experience shows that the expenses in order to guarantee the safety of a dam are little when compared to the costs of its rupture. The author quotes the importance of the use of a database of instrumentation for supporting the preliminary

The principles established on NBR 8681 – *Ações e Segurança das Estruturas* (Actions and safety of structures) [7] conceptualizes the safety of the concrete constructions of a dam. For concrete gravity-dam projects, some verification corresponding to the stability analysis are necessary in order to evaluate the safety of the movements of: sliding, overturning, floating,

The stability of dams must be primary analyzed during the phase of the project. The geometry of the structures and the property of the materials involved must be well considered, as well as the load condition. Some of the basic load conditions are shown on

**Figure 1.** Illustration of the basic conditions of load and lack of stability of gravity concrete dams.

Through Physics, it is possible to explain that the difference of the water level (downstreamupstream) generates a hydraulic gradient between the dam downstream and upstream

tension at base and on structure, deformations, consolidation and vibrations.

analysis of the readings in order to detect problems.

just 4%.

Figure 1.

**3. Application area** 

**3.1. Safety of dams** 

This chapter is organized as follows: Section 2 features the problem statement which addresses the importance of the safety on dams and the risks faced when dam rupture accident occurs. Section 3 describes the application area focusing on the safety of dams, on the conditions of load and on the conditions of the monitoring instrument. Section 4 approaches a "research course". Section 5 describes the used data and the Multivariate Statistical Analysis techniques. Section 6 shows the status. Section 7 shows the results. Section 8 approaches the future researches. Section 9 shows the results.
