平直断层黏滑及动态破裂扩展的实验研究  

Experimental study on stick-slip and dynamic rupture propagation of straight faults

作　　者：董鹏[1,3] 夏开文[1] 郭彦双[2] DONG Peng;XIA Kaiwen;GUO Yanshuang(State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]天津大学水利仿真与安全国家重点实验室,天津300072 [2]中国地震局地质研究所地震动力学国家重点实验室,北京100029 [3]中国矿业大学

出　　处：《岩石力学与工程学报》2018年第A02期3990-3997,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51479131);中国地震局地质研究所地震动力学国家重点实验室开放基金资助项目(LED2016B05)~~

摘　　要：研究断层黏滑的力学特性,观测断层破裂扩展过程,对了解震源过程具有重要意义。基于实验地震方法,对辉长岩平直断层试样进行双轴加载,模拟自然地震现象。在0.05~0.5?m/s加载速率范围内研究加载速率对断层黏滑应力降和周期的影响。通过超高速数字散斑观测系统对断层的动态破裂过程进记录,利用数字图像相关(DIC)技术处理获得断层破裂扩展过程中的位移场以及剪应变场,据此分析断层的动态破裂扩展过程。研究结果表明:(1)在本实验的加载速率范围内,加载速率越低,则黏滑周期越长,平均应力降越大,断层整体滑移量也越大。(2)孕震断层上的成核区域不仅限于一个,断层破裂经历了成核、低速联接以及快速扩展3个阶段,快速扩展的速度接近甚至超过辉长岩试样的剪切波速。(3)断层面上存在一些凹凸体和弱段,造成断层动态破裂扩展过程的复杂性以及断层滑移分布的不均匀性。Study on the mechanical characteristics of stick-slip and the observation of rupture propagation on faults are in favour of getting insight into the earthquake source process. To mimic natural earthquakes,in this paper,the scheme of laboratory earthquake was performed where the gabbro sample of straight fault was loaded bi-axially. The effect of loading rate in the range of 0.05–0.5 μm/s on the stress strop and recurrence interval of stick-slips was investigated. Based on the ultrahigh speed diagnostic system with digital speckle,the dynamic rupture propagation of the fault was captured. With the digital image correlation(DIC) method,the evolution of the displacement field and the shear stress field was resolved. It is revealed that:(1) the recurrence interval,average stress drop and the dislocation of ruptures increase while the loading rate decreases.(2) There can be more than one nucleation region on the earthquake fault and the observed rupture process consists of the nucleation stage,the slow coalescence stage and the rapid propagation stage where the rupture speed can approach or even exceed the shear wave velocity.(3) The asperities and weak segments on the fault are responsible for the complex of the dynamic rupture propagation process and the heterogeneity of dislocation along the fault trace.

关 键 词：岩石力学 黏滑 超高速观测系统 动态破裂扩展 

分 类 号：TU45[建筑科学—岩土工程]