ABSTRACT

Field measurements of acoustic emission in salt mines indicate significant influence of humidity of the mine air on the microcrack activity in the rock mass, e.g. as mild seasonal variations in long-term measurements and as strong variations during the backfilling of large rooms with salt concrete. Laboratory tests were performed to gain more knowledge about this humidity induced microcrack processes in rock salt. Results of mechanical and ultrasonic measurements in the tests are presented and interpreted. The decrease of the flow stress and the rising activity of the acoustic emissions as a consequence of rising humidity in the experiments were caused by the reduction of the cohesion of the rock salt sample due to penetration of moisture into open microcracks and pores of the dilated sample.