2136 operations, including the Polish copper mines of KGHM, comprehensive determination of the full principal stress state is not routinely available at the mine scale; instead, engineering decisions and model calibrations often rely on simplified assumptions or sparse historical measurements. This creates a practical gap: without site-specific stress tensors, it is difficult to reliably reproduce stress-driven damage mechanisms in numerical analyses or to interpret monitoring signals in terms of evolving stability. This limitation is especially important for numerical simulations, where the initial stress field strongly influences predicted convergence, yielded zones, and local failure around excavations. Core-based laboratory techniques exploiting acoustic emission (AE) offer an attractive complementary pathway, because they transfer the measurement effort from the underground environment to controlled laboratory conditions using material that is routinely recovered during exploration drilling. The conceptual basis is the Kaiser effect, i.e., the tendency for AE activity during reloading to remain low until the specimen exceeds the maximum previously experienced stress level, at which point AE increases markedly (Lavrov, 2003; Friedel & Thill, 1990). Building on this stress-memory principle, AE methods have been developed to estimate stress components—and, with oriented core and multi-directional subcoring, to reconstruct the full stress tensor (Villaescusa, Seto & Baird, 2002; Villaescusa, Windsor, Li, Baird, & Seto, 2003; Seto & Villaescusa, 1999). The feasibility and limitations of AE–Kaiser approaches have also been discussed in broader methodological syntheses (Blanksma, 2011; Dinmohammadpour, Nikkhah, Goshtasbi, & Ahangari, 2022). At the same time, recent studies highlight that AE-derived stress estimates are sensitive to lithology and protocol choices, which is particularly relevant when comparing carbonates and sandstones. Loading rate can shift the identified Kaiser point and affect accuracy across different rock types (Zhang, Okere, & Su, 2021), while anisotropy and specimen orientation can modify the clarity and repeatability of the stressmemory signature (Kharghani, Goshtasbi, Nikkhah, & Ahangari, 2021). Additional evidence suggests that stress-memory behaviour may be more complex than a single threshold under certain loading paths (Ma et al., 2025), motivating careful interpretation frameworks and objective criteria, including approaches that combine theory with experimental validation (Bai et al., 2018) and demonstrations in deep applications (Qin, 2019). Against this background, the present pilot study evaluates AE monitoring and Kaiser-effect interpretation during cyclic loading of carbonate and sandstone specimens to test the practicality of obtaining consistent stress-memory indicators for mining-relevant 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.
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