报告地点：教学行政楼706
报告时间：星期五,2022-11-25 15:00 -16:30
报告人：张诗淮 （苏黎世联邦理工学院）
报告人简介：
张诗淮，2019年于北京科技大学获岩土工程博士学位，2019年起受瑞士国家科学基金项目资助于瑞士苏黎世联邦理工学院做博后研究。目前主要研究方向为岩石力学及地质力学，具体包括：1）非常规油气储层岩石时效变形及强度特性；2）地壳应力时空演化规律；3）地壳应力评估测试新方法。研究成果发表于Journal of Geophysical Research-Solid Earth, International Journal of Rock Mechanics and Mining Sciences, Rock Mechanics and Rock Engineering等国内外知名期刊。
报告题目：Spatial Stress Variations within a Fault Zone Revealed by Breakout Observations Within an Array of Boreholes in a Granitic Rock Mass
报告内容简介
The in situ stress state within fault zones is technicallychallenging to characterize. At the Bedretto Underground Laboratory in theSwiss Alps, the breakouts observed in an array of eight inclined boreholespenetrating a major fault zone offer a unique opportunity to characterize thefault-associated spatial stress variations. Synthesizing multiple geophysicallogs, natural geological structures intersecting these boreholes areidentified, revealing a hierarchy of a major fault zone along with secondarystructures. Within the boreholes, breakout rotations occur over multiplescales, spanning individual fractures and the entire major fault zone. Based onthe analytical solution of the stress field around a circular borehole andMohr-Coulomb failure criterion, the observed breakout azimuths are used toinvert the orientations and relative magnitudes of the stresses across thefault zone, revealing a decreasingly critical stress state from afar to thefault zone center. Our work provides a workflow to semi-quantitatively estimatethe in situ stress variations around fault zones in the absence of directstress measurements, which is beneficial to a number of scientific andengineering applications.