The characteristics of the groundwater flow in a rock slope primarily depends on rock joint sets. In particular, the groundwater flow in a rock slope which has random joint sets is very complicated, and the specific methods which to monitor this flow have not been developed. Using dipole-dipole electric resistivity technique, we tried to monitor the groundwater flow behaviour during rainfall in a rock slope site. The interesting resistivity change which was continuously measured at this site is reported, and the relationship between the resistivity change rate and the rainfall quantity is also analyzed.
Sous la pente de roche, les caracteristiques d' eau souterraine dependent de laforme du joint en roche. Dans la roche aux joints aleatoires, specialement, le courd d'eau souterraine est tres complique, et on n' a pas encore mis au point la technique precise pour observer ce cours. Nous avons essaye d'observer le comportement du cours d'eau souterraine sous la pluie, a une pente de roche, par la methode dipole-dipole deresistivite electrique. A la suite d' une mesure continuelle a cet emplacement, un changement interessant de resistive a ete rapporte, en plus, la relation entre le taux de changement de resistivite et la quantite de pluie tombee a ete analsee.
Grundwasserbewegungen in Felsabhagen hagen entscheidend von den Felsrissen ab. Grundwassererstromungen bei Formationen mit unvorhersehbaren Felsspaltensind hier besonders kompliziert, eine klare Erfassung der Strornung ist hier nicht entwickelt. Wir untemahmen den Versuch, mit Hilfe von Elektromessungen, dipole-dipole, die Grundwasserstromung in Felsabhhangen wahrend des Regens zu messen. Wir referieren die Interessanten Ergebnisse regelmaβig durchgefuhrter Messungen zu den Veranderungen entsprechend dem spezifischen Widerstand und analysieren das Verhaltnis der Veranderungen zur gefallenen Regenmenge.
Generally, the groundwater flow in rock slope depends on the direction for the development of rock joints sets, those are very complicated. It is very importance for disaster and environment problems that monitor the groundwater behaviour contained the flow conditions in rock slope. However, the investigations in associate with the continuous monitoring of the groundwater flow in rock slope are very few. Because the electric resistivity methods have been mainly used to make a survey of the aquifer. In this paper, the continuous change of electric resistivity are measured in order to monitor the movement of groundwater flow in rock slope site by dipole-dipole electric resistivity technique on the period of rainfall, and the analysis of groundwater flow in this slope based on the measured resistivity data are carried out. As the results, it is found out that dipole-dipole method is very useful for the monitoring of groundwater flow in rock slope, and the groundwater conditions through the fracture zone and the rock joints in this site are monitored by this technique.
The location of the measurement line and the topography of this site are shown in Fig.1, and this geological profile is shown in Fig.2. The geology of this slope site in which the basic rock mass consists of sandstone, slate and chert formed from permian period to Jurassic period, these rocks are rather hard, but depending on the area in this site, and many joints and fractures are distributed, the locations of these are not confirmed. This basic rock mass are covered with soft rock in which the some joints develop, and one inclined fracture lies in this layer. The near surface of this site consist of the weathered deposits contained silt and clay, and the outcrop of jointed soft rocks is partially observed on the surface of this slope.
From Fig.2, the average dip of this slope is 14, and 96 electrodes are linearly arranged with separation distance 1 m on the surface, and these are numbering from the foot of slope.