practicality of obtaining consistent stress-memory indicators for miningrelevant strata. The overarching motivation is to provide stress information that can materially improve numerical modelling and geomechanical interpretation in settings where the initial stress field is currently poorly constrained. The aim of this research is to evaluate whether acoustic-emission stress-memory testing—interpreted using the Kaiser effect—can provide a practical and repeatable estimate of the pre-existing stress state from oriented core samples collected in KGHM underground mines in the Lower Silesian Copper Basin (Poland). To achieve this, we tested roof- and sidewall-oriented cores from key local lithologies, applied a consistent workflow to identify the Kaiser stress (σK), and used validity criteria to separate reliable responses from non-valid ones. We then examined how the estimated stress and its uncertainty vary with borehole orientation and depth, and we use these findings to propose recommendations for future sampling. 2. MATERIAL AND METHODS The tests were carried out in the Laboratory of Material Research, KGHM CUPRUM Ltd on cylindrical specimens with a 42 mm diameter and a slenderness ratio of 2 (height-to-diameter). The specimens were prepared from drill cores obtained from four roof boreholes and from cores drilled in four sidewall boreholes. The tested material comprised dolomites and anhydrites from the roof interval, and anhydrites and sandstones from the sidewall intervals. 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 prefailure (plastic) state immediately preceding macroscopic failure.
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