Abstract For the commonly-used laboratory frictional earthquake model, unstable slip usually occurs without any end constraint. This experimental design is contradictory to a simple fact: real faults are confined by their surroundings, and the relative sliding is not end-free. To investigate the effects of end constraint conditions on the stick-slip behaviors, direct shear tests are conducted on PMMA sheets with three kinds of pre-crack length, and high sampling rate strain gage array and digital image correlation method are used to monitor the detailed processes of dislocation(stick-slip). We find that pre-crack length has great influence on the intervals of dislocation (stick-slip), the total number of dislocations (stick-slip) that occurs before crack extension, the magnitude of stress-drop and rupture velocity. A transition of the dislocation propagation velocity from sub-Rayleigh to super-shear is observed for PMMA sheets with a long pre-crack, while super-shear velocity rupture cannot be obtained in PMMA sheets with a short pre-crack.

中文翻译：

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不同端部约束程度的剪切断层粘滑破坏实验研究

摘要 对于常用的实验室摩擦地震模型，通常在没有任何端部约束的情况下发生不稳定滑移。这种实验设计与一个简单的事实相矛盾：真正的断层受其周围环境的限制，相对滑动不是无止境的。为研究端部约束条件对粘滑行为的影响，对三种预裂纹长度的PMMA板材进行了直剪试验，并采用高采样率应变片阵列和数字图像相关方法进行详细监测。脱位过程（粘滑）。我们发现预裂纹长度对位错间隔（粘滑）、裂纹扩展前发生的位错总数（粘滑）、应力降的大小和破裂速度有很大影响。