The Experimental Observation On Instability Sliding And Stability Process Of Granite Driven By Elastic Energy Release

From a mechanical point of view,earthquake is a problem of instability and failure of fault driven by elastic energy release.Granite is the main constituent material in the crustal structure.Understanding the evolution process and characteristics of granite frictional sliding instability is of practical significance for us to understand the mechanism of earthquake occurrence,explore the precursory law of earthquake occurrence and its prediction method.In particular,the frictional sliding instability driven by the elastic energy release.Based on this,this paper focuses on the experimental observation of the process and evolution law of granite friction sliding instability,and studies the basic characteristics of granite friction sliding instability driven by elastic energy release and its post-earthquake stability process.The paper designs and makes the granite double-shear friction test device,and uses the high-precision and high-rate data acquisition device to realize the observation of rock friction instability evolution process.Under different lateral pressures,the process of rock friction instability driven by elastic energy released under two typical loading modes of controlled displacement monotone continuous loading and constant displacement loading was observed in detail.The cyclic process of granite friction instability under monotonic loading was observed.The weakening and strengthening of granite friction displacement under low and high lateral pressure are explained.The experimental observation shows that the granite instability sliding will go through three typical stages.They are accelerated sliding stage before instability,unstable sliding stage and post-earthquake stability stage.The nonlinear stability process of granite sliding after friction instability is systematically analyzed.Furthermore,the slip displacement in the stabilization process can be described as a power law relation of evolution time.The experimental observation of rock friction instability sliding under constant displacement loading condition is realized for the first time,which indicates that elastic energy release under this loading condition will drive the self-sustaining development of rock friction instability sliding.Under this loading condition,the scale and stress drop ofthe instability sliding are sometimes even larger and higher than those under monotonic loading.