断层系统中局部断层活动过程的数值分析方法——以Z字形断层为例  

Numerical method for the process of local fault activities of a fault-rock block system:a case of a Z-shaped fault structure

作　　者：王学滨[1,2] 白雪元 马冰[1] 

机构地区：[1]辽宁工程技术大学力学与工程学院,阜新123000 [2]辽宁工程技术大学计算力学研究所,阜新123000

出　　处：《地球物理学进展》2015年第6期2938-2944,共7页Progress in Geophysics

基　　金：国家自然科学基金项目(51374122;51274109);辽宁省科学事业公益研究基金(2014003008);高等学校博士点专项科研基金(20132121110006)联合资助

摘　　要：断层系统中局部断层活动顺序及稳定性的研究对于地震及矿震等自然灾害的预防具有重要的实际意义.通过编写FISH函数对FLAC-3D进行二次开发,分别对Z字形断层系统中4条断层上与剪切和拉伸破坏有关的6种量随时段的演变规律进行了统计.研究发现,首先,位于标本两侧的拐折断层和平直断层交替活动,然后,位于标本中部的平直断层的活动被上述平直断层的活动触发并导致标本整体的失稳.从与剪切应变能释放有关的2种量的演变规律上能发现位于标本一侧的平直断层b0值(事件的频次-能量关系的斜率的绝对值)缺失的明显标志.由于发生拉破坏且释放拉伸应变能的单元较多,所以,在任一时段内,标本中释放的拉伸应变能并不一定比剪切应变能低.本文的研究方法对于复杂断层系统中局部断层的活动顺序及稳定性研究具有一定价值.Determination of the sequence of local fault activities and their stabilities is especially significant for natural hazards＇ prevention,such as natural and mining earthquakes.Through writing FISH functions in FLAC-3D,six quantities related to shear and tensile failures at four faults of a Z-shaped fault structure are presented at different timestep intervals.It is found that,firstly,a bending fault and a straight fault alternatively act,which are at both sides of a sample,and that then the activity of a straight fault at the middle of the sample is triggered,leading to an instability of the sample.The phenomenon that b0value（the absolute value of the slope of the relation between frequency of events and released energy）cannot be calculated for the straight fault at one side of a sample at a few time intervals is related to the rapid liberation of shear strain energy at this fault.Thus,the phenomenon mentioned can be observed from evolution of two kinds of quantities related to drops in shear strain.The number of failed elements due to tension is greater than the number of failed elements due to shear.Therefore,at several timestep intervals,the liberated tensile strain energy can exceed the liberated shear strain energy.The present method proposed can be applied to studies of the sequence of local fault activities and their stabilities for complex fault structures.

关 键 词：断层系统 活动顺序 稳定性 能量释放 剪切应变能 

分 类 号：P313[天文地球—固体地球物理学] P631[天文地球—地球物理学]