报告地点：教学行政楼706 会议室
报告时间：2024-10-18 从16:00到17:00
报告人：Barnaby Fryer（Géoazur, Côte d'Azur University, France）
报告人简介：
Barnaby is a postdoctoral researcher at Géoazur in Valbonne, France. Currently developing injection experiments on 35x20 cm fault surfaces in PMMA, he is interested in the physics of earthquake nucleation and rupture, with an applied focus on Enhanced Geothermal Systems. Barnaby holds a bachelors degree from the Univsersity of Texas at Austin in Petroleum Engineering, a Master’s degree from the TU Delft in multi-component reservoir simulation, and a PhD related to induced seismicity from the Ecole Polytechnique Fédérale de Lausanne in Switzerland.
报告题目：The scale dependence of seismic-rupture arrest
报告简介：
Whether or not energy dissipation is localized in the vicinity of the rupture tip, and whether any distal energy dissipation far from the crack tip has a significant influence on rupture dynamics are key questions in the description of frictional ruptures, in particular regarding the application of Linear Elastic Fracture Mechanics (LEFM) to earthquakes. These questions are investigated experimentally using a 40-cm-long experimental frictional interface. Three independent pistons apply a normal load with a fourth piston applying a shear load, enabling the application of a heterogeneous stress state and stress barriers. After loading the frictional interface to a near-critical state, subsequent unloading of one normal-load piston leads to dynamic ruptures which propagate into the heterogeneous stress fields. The ruptures in these experiments are found to be driven by unconventional singularities, characterized by an ever-increasing breakdown work with slip, and as a result do not conform to the assumptions of LEFM. As these experimental stress barriers inhibit slip, they therefore also reduce the breakdown work occurring outside of the cohesive zone. It is shown that this distal weakening, far from the crack tip, must be considered for the accurate prediction of rupture arrest length. This means that stress barriers arrest ruptures by not just increasing the ‘‘residual’’ shear stress reached in the cohesive zone of the passing crack tip, they also reduce the long-tailed weakening occurring farther behind the crack tip by inhibiting slip and rupture advance. In summary, stress barriers increase fracture energy, reduce energy flux to the crack tip resulting from cohesive-zone weakening, and reduce energy flux to the crack tip resulting from distal, long-tailed weakening. All three of these effects aid in the arrest of the rupture.