ABSTRACT:

According to the demand for the multiple utilization of underground rock caverns such as the underground storage of crude oil, LPG and compressed air, the characterization of hydraulic properties of rock is considered as one of the most important items to be studied. In this paper, the results of in-situ experiments to determine the hydraulic, properties of jointed rock by Crosshole Permeability Test are described. Three dimensional hydraulic conductivities and specific storage were estimated by this test and the form of groundwater flow in the rock has been studied. The results were examined and verified with the borehole TV and crosshole seismic tomography observations.

RESUME:

Selon la demande pour l"utilisation à buts multiples de la caverne souterraine dans le rocher comme reservoir souterain pour emmagaainer de l"heuil brute,du gaz naturel liquefie, et de l"air comprime, la determination des caracteristiques hydrauliques de la roche est considere comme un des fracteurs importants à etudier. Dans cet article, les resultats de l"essai in-situ de permeabilite avec les trous fores pour determiner les caracteristiques hydrauliques du rocher fissure sont decrits. Les conductivites hydrauliques à trois dimensions et le volume specifique de la retenue sont estime par cet essai et le reseau des lignes de courant d"eau dans le rocher est etudiee. Les resultats sont examines et verifies par le televiseur des trous fores et l"observation tomografhique seismique des trous fores.

ZUSAMMENFASSUNG:

Aufgrund des großen Bedarfs an vielfach nutzbaren Gesteinskavernen, wie zum Beispiel fuer Rohöl, fluessiges Propanges und Druckluft, hat die Untersuchung der hydraulischen Eigenschanften von Gestein ueberragende Bedeutung. In der vorliegenden Studie werden die Ergebnisse eines Experiments vor Ort diskutiert, das sich die Bestimmung der hydraulischen Leitfahigk.it durch Pruefung der Querbohrungsdurchlassigkeit zum Ziel geserzt hat. Die Untersuchung erlaubte die Schatzung hydraulischer Leitfahigkeiten und der spezifischen Lagerung im dreidimensionalen Raum, und die Abflußform des Grundwasser im Geistein konnte untersucht werden. Pruefung und Verifikation der Ergebnisse wurden mit Hilfe von Bohrloch-Fernsehtechnik und seismischen Querbohrungs-Schichtbilddarstellungen vorgenommen.

1. INTRODUCTION

In order to evaluate the hydraulic properties of rock mass, the single-hole injection testing has been widely adopted. However, in particular, for jointed rock, some disadvantages have been. encountered with this test, i.e. each of the test results only indicated the very local properties for the test area and thus the measured values varied in orders. In the past, a frequency distribution for such values was often examined and the average value was determined statistically, however it is considered such a method is inadequate of not accounting for highly permeable zones, which might exist in a rock mass. In addition, this test is not suitable for estimating anisotropic properties, which are considered to be generally governed by joint geometry.

In this respect, the authors have studied the application of a crosshole permeability test, using numbers of boreholes, in jointed rock. This paper describes the results from in situ experiments for two types of rock mass. One of these was an application to a moderately jointed granodiorite and the other was to a heavily jointed rhyolite. An effort has been made to evaluate the hydraulic conductivity and specific storage at two sites, and particularly.

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