| Abstract: | As a relict of former subsurface basalt mining activities within the municipal area of the city of Mendig (Germany) an area of about 200,000 m² of disused pillar-supported mining openings still exists at about 15–20 m below the current ground surface. After the shut-down of mining, numerous pillars experienced brittle deformation and several surface collapses occurred. To prevent any further harmful damages, a risk assessment with modeling of relevant parts of the mining openings is carried out currently. The geomechanical input data for modeling are based on the results of numerous laboratory tests. The test results indicate, that pillar failure is strongly influenced by a combination of particular pillar properties such as geomechanical properties (uniaxial compression strength) as well as geometric properties (width-height-ratio, inclination of pillar longitudinal axis). |
