岩石应力敏感曲线机制分析

THE MECHANISM OF STRESS SENSITIVITY CURVES OF ROCK

根据固体力学的有关知识,研究了岩石应力敏感曲线测试过程中的机理问题。岩芯应力敏感曲线测试时因封套的塑性变形,使得加载曲线与卸载曲线产生了较大的差异,也夸大了岩石的应力敏感程度。实际上,应力敏感测试时,岩芯只产生弹性变形,而不产生塑性变形。加载时封套有塑性变形,卸载时封套和岩芯都无塑性变形。卸载曲线的应力敏感程度,包含了封套的弹性变形部分。扣除封套的变形因素,岩石自身的应力敏感程度极其微弱。

Based on the fundamentals of solid mechanics,a study is conducted in this paper on the mechanism of measurement of stress sensitivity curve of rocks.Due to the plastic deformation of core sleeves,the up-load curve and the down-load cure differ a lot,which exaggerates the stress sensitivity of rocks.Actually,in measurement,cores yield only elastic deformation and not plastic deformation.In up-load process,core sleeve yields plastic deformation,and in down-process,both core sleeve and core do not yield plastic deformation.The stress sensitivity of rock in down-load process includes part of elastic deformation of core sleeve.Without the deformation of core sleeve,the stress sensitivity of core is weak and negligible.