Dynamic processes in salt rocks - a general approach for softening processes within the rock matrix and along bedding planes

摘要

Understanding of the relevant failure processes is a prerequisite for dimensioning of underground mining openings. Investigation of brittle failure processes in potash mining and their simulation by rock mechanical modelling clearly demonstrate that the fracture mechanisms of slender and compact pillars are quite different. The collapse of a compact pillar is only possible if besides an overall softening of the rock coevally an accessory loss of cohesion occurs at pronounced weakness planes, particularly along the bedding planes towards the hanging and the underlying layers of the pillars. For the description of the different dynamic processes specialised constitutive models are available, which were verified with various case studies, Exemplarily, the dynamic failure event that actually occurred at the mined top of a domal carnallitite structure has been recalculated. The pronounced seismological s-wave signal which had been recorded during the event has been convincingly referred to development of a shear fracture as the relevant failure mechanism.