A research for earthquake source mechanics based on the contact theory

本项目旨在研究基于主要在摩擦学领域发展起来的接触理论的故障力学。研究结果表明：(1)接触表面的塑性变形对接触表面的变形起着关键作用。在岩石实验中通常观察到的滞后和永久偏移量，在加入塑性变形模型时出现在计算机模拟中。这些结果以两篇论文的形式发表在《地球物理杂志》上。(2)通过压痕试验研究了岩石摩擦的速率特性。结果表明，试件的变形速率强烈依赖于压头的碰撞速度。这一现象被解释为压头和样品之间的局部加热效应，这可能会降低样品的粘度，结果发表在GePhys.Res.Lett上。(3)进行了计算机模拟，研究了DC作为速率和状态变量摩擦定律中的参数的物理意义。计算机模拟的结果与他人的实验观测结果相吻合。发现DC与粗糙接触的真实局部区域相关。(4)与摩擦学领域的研究人员沟通，讨论摩擦、磨损等相关问题。我向他们介绍了一些岩石力学方面的工作，这些工作以两篇论文的形式发表在《摩擦学家》杂志上。英文版也发表在日文《摩擦学》杂志上。

This project aims to investigate the fault mechanics based on the contact theory that has been mainly developed in the field of tribology. The results obtained are summarized as follows :(1) Plastic deformation at asperity contacts was found to play a key role in the deformation of contacting surfaces. Hysteresis and permanent offset, which have been typically observed in experiments on rocks, appeared in a computer simulation when a plastic deformation model is incorporated. The results were published as two papers in J.Geophys.Res.(2) An indentation test were performed to investigate the rate-dependent properties of rock friction. The result showed that the rate of deformation of the sample was strongly dependent on the collision velocity of the indenter. This phenomenon was interpreted as an effect of local heating between the indenter and the sample, which may reduce the viscosity of the sample, The results were published in Geophys.Res.Lett.(3) A computer simulation was performed to investigate the physical meaning of Dc that appears as a parameter in the rate and state variable friction law. The results of the computer simulation agreed with the experimental observations done by others. Dc was found to be correlate to the real local area of asperity contacts.(4) I tried to communicate with the investigators in the field of tribology to discuss problems of friction, wear and other related issues. I introduced some works done in the rock mechanics to them, which was published as two papers in Tribologist. The English versions were also published in Japanese J.Tribology.