声发射及Kaiser效应揭示广东河源地区历史应力特征OA

The Heyuan area is located on the eastern margin of the South China Block,where large granite outcrops are prominently exposed.To investigate the stress history of the granite in this region,a series of uniaxial compression tests were conducted.The stress characteristics of the granite were analyzed based on the Kaiser effect observed in acoustic emission(AE)signals.The AE results indicate that:1)during monotonic uniaxial compression,the AE activity can be divided into three distinct phases:a low-activity phase,a rapid growth phase),and a burst phase;2)in the case of incremental cyclic loading,the cumulative AE ringing counts exhibit a stepped increase;and 3)the constant-amplitude cyclic loading demonstrates a typical Kaiser effect.The G-P algorithm was employed to calculate the correlation dimension of AE ringing counts,characterizing the fractal scaling of damage evolution.The point with the minimum correlation dimension,located near the approximate Kaiser point,was identified as the critical stress point satisfying the Kaiser effect.Furthermore,the Felicity ratio derived from cyclic loading data was used to validate the Kaiser effect.Based on this analysis,the maximum historical differential stress of the granite in Heyuan was determined to be 79.1 MPa.It is inferred that the granite formed at a depth of approximately 3.9 to 6.6 km,and that block uplifts since the Cenozoic era have caused a surface rise by about 3.5 to 6.2 km in the Heyuan area.The result provides new evidence for the study of tectonic evolution in south China.