Geodynamic phenomena in hazardous fault zones affected by extensive surface mining in Central Europe
Abstract
This article presents a comprehensive interpretation of long-term and very precise levelling and tiltmeter monitoring in an exploration gallery opened 42 years ago in the Krusne hory Mts. The importance of the detailed investigation of the crystalline rock mass is a result of the nearby brown coal open pit mine, which prolongated the natural 500-m long fault slope by an additional 200 m of the working face.
Slope movements may be generated under such conditions. Moreover, Jezeri Castle (gothic monument) could be affected by slope instability.
The exploration gallery together with the surrounding slope serve as a natural laboratory for registering a) rock mass block tilting; b) possible elastic uplift resulting from an enormous mass unloading of basin sediments during coal mining; and c) tectonic movements along the Krusne hory fault (part of the ECRIS). The entry section of the gallery showed long-term gravitational creep of the surface formations, which has been accelerated due to the mining activity.
On the other side, the back part of the gallery showed a long-term uplift, and the very end of the gallery is without any signs of exogenous or anthropogenic influence. Strict seasonal variability in the trend of rock mass tilting with typical winter/spring vertical acceleration corresponds to the landslide activity in the gallery surroundings.
The overall evaluation of the monitoring has not indicated a significant risk for the Jezeri Castle. It is a successful result of geotechnical works from the 1980s and long-term monitoring, which was incorporated into mining projects and proper hazard management.