Some Comments on Dynamic Stability of Rock Slopes


Authors: Holub K, Stodulková S

Published in: Bulletin of Geosciences, volume 74, issue 2; pages: 181 - 184;

Keywords: seismic waves, blasting operation, stability of rock slope, Miocene coal basin, Bohemia,

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Individual sedimentation cycles in the Miocene coal basin in the Northwest Bohemia, where many of open-pit brown-coal mines are situated, contain sometimes some sideritic mudstone interlayers. In order to facilitate continuous operation of the large excavators, these hard layers must be disintegrated by blasting operations prior to coal seam exploitation. This represents an essential form of the stripping operations.
Dynamic effects of these blasting operations on the rock slope stability are evaluated according to the critical values of particle velocities for sliding and failure of stripping slopes in the open-pit mines. The source of seismic waves was in our experimental measurements modelled by a cylindric charge of explosives which was put into borehole and tamped by sand. The whole charge was fired instanteneously, i.e. without any delay even when charges in two and/or three boreholes were situated. Seismic waves, namely radial component of particle velocities, generated by explosions were recorded at three sites of observation in the near zone of the seismic source using pairs of velocigraphs with different sensitivity at each of them.
Resulting values of particle velocities were compared with macroscopic effects of individual explosions on the state of rock slopes which were documented by photos before and after every explosion.