Experimental Research on In Situ Stress Measurement Using the Kaiser Effect

ABSTRACT To investigate the Kaiser effect (KE) stress level of different lithological rocks, acoustic emission (AE) tests were performed on borehole cores specimens of different buried depths in the Ordos Basin. The effects of circulation paths, cyclic peak loads, and confining pressure on the rock KE were explored. The reasonable cyclic loading mode of the AE–deformation rate analysis (DRA) method was proposed. The first circulation peak stress (σp) of siltstone, fine sandstone, and gritstone is less than 27 % of the uniaxial compressive strength (σc), and sandy mudstone is less than 40 % of σc, and medium sandstone is less than 17 % of σc, and mudstone and limestone are less than 13 % of σc, and subsequent cycle σp does not exceed 63–70 % of σc. The mechanism of high stress on KE was revealed. The relationship between the KE under triaxial and uniaxial loading conditions was discussed. When the confining pressure is within 10 MPa, the in situ stress measuring by KE under uniaxial loading can be directly adopted. The impact mechanism of high stress on KE and the AE-DRA method should facilitate future application of KE and improve the correctness of data interpretation.