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Continuous strain monitoring in the rock foundation of a large gravity dam

Abstract:

The occurrence of tension fractures in the granitic bedrock at the upstream toe of a dam and unexpected water percolations downstream in the rock foundation gave rise to an extensive investigation program. For the continuous monitoring of strain along different boreholes in the rock the Sliding Micrometer ISETH was applied. This is a portable high precision instrument to measure the distribution of strain along a borehole with the base length of 1.0 m. The accuracy of the setting in the consecutive Points is about k 0.003 mm. This makes the device suitable for detecting extremely small deformations which are likely to be encountered in hard rock masses. From the strain distribution along several boreholes with a total length of approx. 400 m a clear picture could be obtained with respect to the location of particular joints which opened as a result of the reservoir filling. The detailed knowledge of the foundation behaviour allowed the necessary remedial measures to be taken against unpermitted water percolations under the dam body.

Authors:

Kovári, Kalman and Peter, Guy

Index Terms:

rock; TunnelingGroup; Kovari, Kalman; Peter, Guy

Further Information:

Date published: 1983