【摘要】 在雁列区贯通之前及过程中,研究雁列构造复杂的相互作用及一些力学量的时空分布规律,对于地震前兆研究具有积极意义.为了延缓岩石材料的破坏过程,在FLAC-3D的应变软化模型中引入了断层和岩石单元的非均质性.为了探索事件的迁移及断层失稳前兆规律,在两条断层的内、外侧岩石上布置若干被监测单元,在标本全场内对大于某一临界值的剪切应变降进行捕捉.研究发现,拉张雁列区内的破坏区不启动于断层端部,这与两条断层的相互影响和作用有关;在雁列区贯通之前,剪切应变降由远及近迁移,雁列区曾一度成为空区,随后空区消失.剪切应变降密集分布在除了雁列区附近的断层附近,反映了大量中等强度的单元发生破坏,而在雁列区贯通之后,剪切应变降总体上回归平静.在同一时刻,不同断层上被监测单元的剪切应变演变规律复杂:同步、不同步共存,这反映了两条非均质断层之间复杂的相互影响和作用.更多还原

【Abstract】 During and prior to the jog failure,studies of complex interactions among faults and spatiotemporal distributions of some mechanical quantities of echelon faults are especially significant for us to explore seismic precursors.In order to delay the failure process of rock materials,heterogeneities of rock and fault elements are taken into account.Numerical calculations are conducted by use of FLAC-3Dwhere a proposed heterogeneous strain-softening model is included.To investigate migrations of events and unstable precursors or abnormalities,we arrange some monitored rock elements at both sides of two parallel faults constituting an extensional echelon fault,and we also capture larger shear strain decreases within the entire specimen including the echelon fault.It is found that the generated failed zones in the jog can originate from some positions of a fault,rather than its tip,which is related to interactions among two faults.Before the jog failure,shear strain decreases migrate from far away toward the jog. Thus,the jog once becomes vacant.Afterwards,the jog is failed and the gap disappears.Shear strain decreases intensively distribute in the vicinity of a majority of faults except for fault segments close to the jog,suggesting failures of a number of fault elements with moderate strengths. However,after the jog failure,shear strain decreases tend to be silent in total.At the same stress acting on the specimen including an extensional echelon fault,shear strains of different monitored elements at different faults exhibit both synchronized andasynchronized changes.These complex phenomena stem from complex interactions among two heterogeneous faults.更多还原