Non-destructive investigation on small earth dams using geophysical methods: Seismic surface wave multichannel analysis (masw) and s-wave refraction seismic methods

Abstract

The application of non-destructive methods of investigation in dams, such as refractive seismic analysis and multichannel surface wave analysis (MASW) are increasingly effective from the point of choosing the best dam site, as well as in the phases of construction and maintenance of the structure. Considering that the objective of the use of the geophysical surveys in the dam structure is to detect the internal flow of fluids, to detect the presence of voids and/or craters, to find possible fracture zones and to identify variations in the saturation level of the massif, characteristics related to the permeability and directly linked to the stability of the dam, the geophysical methods stand out as excellent tools because, unlike probes, for example, they can cover a large area of study quickly and with a good cost effectiveness. This paper aims to present the results of the correlation between the multichannel surface seismic wave analysis (MASW) method and the S wave seismic refraction method in two small earth dams in the countryside of the State of São Paulo, Brazil, more precisely in the cities of Cordeirópolis and Ipeúna. The main goal was to obtain the depths of the rocky top and the saturated / unsaturated zone of the earth dams using seismic tests under conditions of lack of information about the construction of the dam. The application of geophysical methods in dams that do not previously have important information (presence of drainage blanket, vertical / horizontal filters, for example) proves to be a very interesting non-destructive investigation technique.