Micromechanics in frictional dynamics of faults

本项目旨在研究两个粗糙表面之间的接触力学。首先，利用三维表面轮廓仪研究了表面形貌的测量方法。提出了一种新的数据采集方法。论文1（见下文）已提交，其中包括研究结果。我们还利用上述方法获得的三维表面数据进行了计算机模拟。研究发现，接触颗粒的塑性行为在加载和卸载过程中起着重要的作用，塑性行为可以解释加载和卸载过程中的滞后现象。研究结果见论文1。为了研究波在接触面上的传播，进行了一系列的实验。将实验结果与波传播理论进行比较，发现节理对高频传播的纵波和横波具有粘弹性。结果已在论文2中提出（见下文）。关于发起滑移，已经发表了两篇论文，这两篇论文在本报告的另一面显示。对滑移起裂机理进行了精确研究，并将实验结果与接触理论进行了比较。该理论成功地解释了实验结果。因此，我们可以比以前更精确地理解滑移起生的机制。在这个项目中获得的所有结果都在一个单独的卷中报告。论文1 . yoshioka，法向载荷作用下接触面的弹性和塑性行为：基于三维表面形貌的计算机模拟，提交给地球物理学报。2 .吉冈和菊池，节理对透射波的粘弹性响应，地球物理学报。卷。

This project has been carried out to investigate the contact mechanics between two rough surfaces.First of all,measurement method of surface topography was examined by use of a three dimensional surface profilometer. A new data acquisition method was proposed. Paper 1( see below ) has been submitted in which the results are included. We also performed a computer simulation using the three dimensional surface data acquired by the method mentioned above. We found that plastic behavior of contacting asperities plays an important role and hysteresis in loading and unloading processes can be explained by the plastic behavior. The results were reported in Paper 1.A series of experiments have been conducted to investigate wave transmission across a contacting surface. Comparing the experimental results with the theory of wave transmission, we found that a joint behaves visco-elastically to high frequency transmission P- and S-waves. The results have been presented in the Paper 2( see below ).As to the initiation of slip, two papers have been published which are shown on the other side of this report. The mechanics of initiation of slip were precisely studied and the experimental results were compared with a contact theory. The theory successfully explains the experimental results. Thus we can understand the mechanics of initiation of slip more precisely than previously done.All the results obtained in this project were reported in a separate volume.Paper 1 N.Yoshioka, Elastic and plastic behavior of contacting surfaces under normal load: A computer simulation using three dimensional surface topographies, submitted to J. Geophys. Res.Paper 2 N.Yoshioka and M.Kikuchi, Visco-elastic response of joints to transmission waves, submitted to Geophys. Res. Lett.