La glauberita es un sulfato sódico que se explota con fines industriales. En el año 2002 en los depósitos evaporíticos miocenos de la formación Yesos y Anhidritas de Zaragoza se encontró glauberita en profundidad en una campaña de sondeos. Mediante la técnica geofísica de la tomografía eléctrica se han llevado a
cabo una serie de perfiles de resistividad eléctrica del terreno. Los datos obtenidos en el estudio se han comparado con la información previa de los sondeos y se ha podido constatar que partiendo de estos, es
posible obtener información de los depósitos y observar como evolucionan lateralmente. Debido a la importante presencia de encajante no se ha podido definir el rango de valores geoeléctricos de resistividad
propios de la glauberita pura pero si se han reconocido estructuras kársticas y deposicionales.
The opening of abandoned salt mines whit the idea of prepare cultural routes requires the use of hard machinery in abandoned places. The erosion caused by salt disolutions damage the mine structure, being dangerous far restoration and visiting purposes. Planed jobs were the opening of a new gallery to prepare around route and restoring the part of the salt mine that will be open to the public. Ground penetrating measurements have been used, first to lacate the position and depth of underground scour hales and subsurface voids in the ground and in the solid salt mountain, and second, to study the vaull and gables end in the salt mine galleries. Three antennas were used in his job, with 100 M Hz, 300 M Hz and 500 M Hz center frecuencies. Radar data has lacate hales in the first meters under the foor of the mine galleries and into the contact between the salt mountain and the cover materials. The analisys of the anomalies also shows scour hales into the slag heap caused by the flowing water which erases the soft materials. These areas are not safety places far mining jobs. This work try to provide safety measurements to the salt mine workers and try to assists to the tourist mine maintenance planning.
Ground penetrating radar is usually employed far non-destructive evaluations and maintenance of roads and bridges. This report describe the study of an embankment where a bridge will be built due to the construction of a new road. The geology in this place, where the foundations of the bridge will be emplaced, are formed by hint sands layers between conglomerates ones. Flowing water erases the sand causing hales and possible landslides, which could be damaging far the bridge. The study of the embankment with a ground penetrating radar allows to know the thickness of the sand Layers and the possible hales placed into them. An antenna with center frecuency 100 M H z was used attending the characteristics of the emplacement. The radar data shows among sorne other things, the different reflectors due to the conglomerate, the sand layers and their thicknesses. The presence and the emplacement of several hales in the layers are also observed. These results show where the faundations must be properly placed. A comparison with a geological profile was perfomed to assure the results.
Accurate identification of frames into concrete rein forced walls in a nuclear power plant was required because of maintenance labours. Several cuts in the concrete, including the frame, were planned. The cutting fines were designed to avoid as much as possible the frame bars. To perfom this work the ground penetrating radar has been used. The use of ground prenetrating radar techniques allow to determine the vertical and horizontal position of the frame bars. GPR detects also other reflectors into the walls. The electric properties contrast between the concrete and the steel of the frame gives reflections clearly detected in the records. This near sur face study requires lo use high reso/ution antennas with a very high center frecuency. The measurement precission required in the work was obtained using a special marker to carry the antenna, specially design for this job. The marker allows to know the position of the antenna on the wall with a precission of centimeters. The measurements were acquired from one antenna with a center frecuency of 1000 MHz, with a SIR 10 system of Geophysical Survey Sistems lnc. An experimental test made in a scale model help to the interpretation of the records. A later and careful treatment in laboratory, using all the records obtained in the nuclear power plant, applying vertical lowpass and highpass filters and horizontal lowpass filter was perfomed, to place correctly the bars into the concrete.
Several kilometers of tunnel have been excavated to extend a metropolitan underground system. In some places, where the subsurface is mainly composed by gravel and sands, water can easly penetrate causing problems to the tunnel and the stations. In order to avoid such problems, a jet-grouting injection was carried out. To check the continuity of the jet-grouting a Ground Penetrating Radar analysis was applied. The radar used is a SIR 10 of Geophysical Survey Systems Inc., with a center frecuency antenna of 100 MHz, prepared for urban jobs. A good determination of the variantion of the thickness of the jet-grouting layer was obtained, although several difficulties, specially the irregular topography, were to be solved. Three boreholes to determine the quality and thickness of the jet-grouting in three different places provided the right calibration of the involved radargrams. During the processing of the data, several filters had to be applied to discriminate the radar signals from noise, coming mainly from the electrical system of the tunnel.