Development of 3D models for determining geotechnical-geological risk sharing in contracts—dores de guanhães/mg/brazil hydroelectric powerplant case study

Abstract

Discussions concerning the type of contract to be adopted, the responsibilities on risks and possibilities of risk sharing in construction works are time consuming during the formatting of the contracts and, often, last until its closure. Within the main difficulties encountered are the lack of data and subjectivity in the interpretation of available information. In order to reduce these uncertainties in models and the sharing definitions, a research project was proposed focusing on the development of a methodology based on an integrated three-dimensional model to support the risk reports and the definition of risk limits assumed by each stakeholder. Available information from, Dores de Guanhães Hydroelectric Power Plant, was integrated in such environment. From geo-structural point of view the main features found are thrust faults of NNE-SSW direction, which are truncated or displaced by a less intense system in NW-SE direction, affecting granite-gneiss rocks of Açucena Granite belonging to the Mantiqueira Complex (Poente and Guanhães Energia, Basic Project Studies HHP Dores de Guanhães-MG, 2008). Data provided by the construction owner have been uploaded in the 3D modelling software, along with the regional images and structural and field data. Geophysical analyses (dipole-dipole array) were performed and included in the model with a thorough discussion of its possible benefits in general interpretation. Finally, the use of the consolidated 3D model is discussed within a tunnel excavation risk assessment methodology.