Effect of Rock Lithology and Reloading Direction on Rock Stress Memory

Abstract

Abstract The Kaiser effect (KE), as a presentation of rock stress memory, has been widely used in in situ stress measurement because of its convenience and economy. However, the influence of rock lithology and directionality on the KE have not been answered yet. To solve this question, three-stage loading Brazilian tests were conducted on three types of rock disks in this study. The specimens were rotated with a certain rotation angle θ (5°–90°) before the third-stage loading, and the jump point method and bilinear regression method were selected to recognize the Kaiser points. The results suggested that significant KE occurred in the three rock materials under the Brazilian test and that the KE directionality of rocks with different lithology varies greatly. The KE gradually fails as the rotation angle increases. The critical angles of granite, marble, and sandstone are 13°, 60°, and 5°, respectively. Besides, the directionality of the KE is closely related to the distribution of microcracks inside the rock and the critical stress of crack propagation. This study could provide a reference for experimental design and error analysis of in situ stress measurement by the acoustic emission method in civil and geotechnical engineering.