Bohrtechnische und baubetriebliche Auswirkungen von Bohrlochinstabilitäten auf die Bohr- und Sprengarbeiten beim Bau des Flusskraftwerks Rheinfelden/Baden

Technical and operational aspects of borehole instability on drill and blast works at the Rheinfelden Hydroelectric Power Plant.

Since 2003, a new Hydroelectric Power Plant has been under construction in the river Rhine near the city of Rheinfelden/Germany. The new Rheinfelden power plant with a projected power capacity of 100 MW mainly consists of a new concrete dam and a new powerhouse as a replacement for the old facilities constructed in the late 19th century. The construction of the powerhouse and the increase of the available river gradient required extensive loosening blasts in the riverbed, which is formed by Triassic limestone and alluvial river deposits. In the course of the drill and blast works, it was observed that unstable rock mass sections and borehole instabilities influenced the drilling, loading and blasting of the rock in many ways. In order to ensure a defined loading in loose alluvial deposits and faulted rock, extensive changes were made to the drilling and blasting methods, for instance insertion of plastic casings or the use of the RBS cased drilling method. The implementation of these measures enabled the works to be completed successfully. This paper gives the basic outlines of the project and the techniques used, and summarises some of the findings on the interaction of geology on the one hand and technical and operational aspects of drilling and blasting on the other hand.