2137 2.1 UCS testing and preparation of samples The UCS tests were performed using a Walter + Bai DP 100 S strength testing machine, providing controlled axial loading of the specimens (Figure 1-left). The system was equipped with an external ZEPWN CL18 load cell, which enabled accurate, continuous registration of the force range during the UCS test and reliable correlation of the loading path with the recorded seismoacoustic (AE) response (Figure 1-right). An acoustic sensor was mounted directly on each cylindrical specimen using dedicated holders and rubber bands to ensure stable coupling during loading. The measurements were conducted under a cyclic, stepwise loading scheme, with repeated load increments of +5 kN followed by partial unloading of −2.5 kN, continued until the specimen reached a pre-failure (plastic) state immediately preceding macroscopic failure. Figure 1 – Equipment for UCS testing (left) and accelerometer mounted on cylindrical rock sample (right) 2.2 System for seismoacoustic measurements System for acoustic emission is based on the AMSY-6 a multi-channel measurement system produced by Vallen Systeme GmbH Germany. This system can be applied to detect, measure and locate acoustic sources comes from material failure processes on microscopic level in different materials including rock samples. Presented systems with dedicated software (Vallen AE Suite software) is a comprehensive system for measurement, store and analysis of recorded data. Entire system incorporated the following elements: master box MB2-V1, dual channel signal processor ASIP-2, preamplifier AEP5 (H) and sensors VS45-H and VS900-M. System can be extended with application of multi-chassis setup up to 254 AE channels. Configuration of the system that was applied during measurement of rock samples is presented in Figure 2.
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