闭合裂纹面相互作用的实验研究

为了研究地震过程中断层面的相互作用,设计了四类裂纹面状况不同的断裂力学实验。实验结果表明,裂纹面的状况对于含裂纹材料的σ_c(2^1/2)值有强烈的影响,并利用断裂力学的原理对结果进行了分析。 实验中解决了如下技术关键: 1.可用三点弯曲、局部受拉、单面启裂、双面贯穿的方法,在脆性材料板状试件（玻璃板、岩石板）以及有机玻璃板中预制中心穿透裂纹。 2.在裂纹端部预计裂纹扩展的区域内粘贴电阻应变片,用以判断并测量裂纹初始扩展及其相应的破坏应力σ_c的方法。

EXPERIMENTAL STUDY OF INTERACTIONS BETWEEN TWO FLANKS OF A CLOSED CRACK

In order to investigate the interaction between the two flanks of a seismic fault in the course of an earthquake, four groups of fracture experiments with different states of crack surfaces have been made. The experimental results showed that the states of crack surfaces have strong effects on the critical value of σ_c for specimens with crack of length 2a. The experimental results have been analized according to fracture mechanics.The following key techniques have been resolved in our experiments:1. A new method to produce pre-cracks in centre of the specimen has been used. Central penetrating cracks in plate specimens of glass, plexiglass and rock can be produced by means of three points bending which leads to local tension and crack initiation at one side of the specimen and penetrating the two sides.2. The strain gauges were placed at the crack tip areas, across which the crack are expected to grow, to monitor the crack initiation and to measure the corresponding strength σc of the experimental materials.