Abstract: It is important for active fault research and seismic hazard assessment in urban area to study the existence of buried active fault and its possible effect on the earth's surface.Many geophysical and geo～chemical techniques have been developed for exploration of buried active fault,and advanced remote techniques have been used in measurement and analysis of deformation on the earth's surface caused by earthquake on buried fault.However,the relationship between buried seismogenic fault and surface deformation and rupture caused by earthquake needs to be further studied.It is helpful for understanding rupture propagation along buried fault in loose sediment to study the evidence of fault sliding in the overlying sediments with simulation experiments.In this paper,rupture propagation along strike-slip fault in bed rock towards the overlying sediment layer has been studied with simulation experiment and deformation field on the surface of sediment layer has been observed using digital speckle correlation method,in which the effects of fault displacement and thickness of sediment layer were mainly analyzed.The research results indicate that a deformation and rupture zone composed of tension and shear fractures along the projection line of fault in bed rock is gradually formed in the sediments as the fault slips,given a constant thickness of the sediment layer.The larger the fault displacement is,the larger the width of deformation zone and the deformation intensity are.However,the width of deformation zone will keep constant when fault displacement exceeds a critical value,but the deformation will only become more concentrated as fault displacement increases.For a same fault displacement,the thicker the sediment layer is,the wider the deformation and rupture zone controlled by the bed rock fault will be,i.e.the larger the influencing extent of the fault is.However,when the sediment layer exceeds a critical thickness,the deformation pattern of sediment layer is changed.There exists no deformation zone consistent with the strike of fault in bed rock but a large-scale tensile shear rupture zone oblique to the fault strike.The experimental results imply that the critical fault displacement and the critical sediment thickness play important roles in determining the surface deformation and rupture caused by buried fault generated earthquake.

Key words: buried strike-slip fault, simulation experiment, digital speckle correlation method, fracture propagation

摘要： 通过模拟实验研究了基岩中走滑断层在上覆沉积层中的破裂扩展特征,利用白光数字散斑相关方法分析了沉积层表面变形场的演化过程,重点研究了基岩断层位移和沉积层厚度的影响.结果表明,在沉积层厚度一定的情况下,随基岩断层的滑动,沉积层中围绕断层投影线逐渐形成一个变形带以及由张性破裂和剪切破裂组成的破裂带,基岩断层的位移越大,沉积层中的变形带越宽、变形越强烈;但当基岩断层位移超过某一临界值后,变形带宽度将保持稳定,只是变形随断层位移增加而更集中.对于同样的基岩断层位移,沉积层厚度越大,受基岩断层控制的变形破裂带越宽,即基岩断层的影响范围越大;但当沉积层厚度超过某一临界值时,沉积层的变形发生了变化,沉积层表面并不存在与基岩断层走向一致的变形带,而是发育了较大尺度、与基岩断层走向斜交的张剪性破裂带.实验结果意味着,临界断层位移和临界沉积层厚度对于确定隐伏断层发震产生的地表变形和破坏具有重要意义.

关键词: 隐伏走滑断层, 模拟实验, 数字散斑相关方法, 破裂扩展