PILOT STUDY ON IN-SITU STRESS ESTIMATION IN CARBONATE AND SANDSTONE STRATA USING ACOUSTIC EMISSION AND THE KAISER EFFECT *M. Jóźwik1, K. Fuławka2, M. Szumny2, D. Nitek1 1 Laboratory of Material Research, KGHM CUPRUM Ltd. Research & Development Centre, Poland (*Presenting author: marcin.jozwik@kghmcuprum.com) 2 Rock Engineering Department, KGHM CUPRUM Ltd. Research & Development Centre, Poland ABSTRACT Reliable determination of the in-situ stress field is a critical prerequisite for safe and efficient mine design, particularly in deep underground operations where high stresses contribute to excavation instability, seismic events, and rockburst hazards. Traditional stress measurement techniques, such as overcoring or hydraulic fracturing, are costly, timeconsuming, and logistically difficult to apply in active mining environments. For this reason, seismoacoustic methods based on laboratory testing of oriented core samples have gained renewed interest. One promising approach is the use of acoustic emission (AE) testing during cyclic uniaxial loading of cores, where the Kaiser effect—the absence of significant AE activity until the previously experienced maximum stress is exceeded— provides a potential indicator of the historical stress memory preserved in the rock. This paper presents the results of pilot investigations conducted on carbonate (dolomite and anhydrite) and sandstone samples collected from a deep underground copper ore mine in Poland. The study was designed to verify the applicability of AE methods for reconstructing principal stress magnitudes and orientations in sedimentary strata characterized by variable porosity and anisotropy. A series of uniaxial cyclic loading tests were performed using a seismoacoustic monitoring system. The analysis focused on identifying the Kaiser point in successive loading cycles. The pilot results confirmed that the Kaiser effect can be observed in compact carbonate rocks with relatively low porosity, providing a reasonable estimate of historical stress levels, while sandstones with higher porosity showed less distinct behavior and greater variability. Based on the experimental observations, a preliminary methodology was developed for conducting AE-based stress memory tests in mining conditions. The findings demonstrate both the potential and the constraints of applying seismoacoustic emission testing as a complementary method for in-situ stress estimation in deep Polish mines. Importantly, the pilot data will serve as input for refining large-scale numerical models of rock mass behavior, thereby strengthening their predictive capacity and supporting safer mine design.
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