不同破坏类型岩石的声发射及分形特征研究

Study on Acoustic Emission and Fractal Characteristics of Different Damage Types of Rock

为了研究在单轴压缩下不同破坏类型岩石的声发射及分形特征,利用声发射监测仪和岩石力学伺服试验系统对砂岩和泥岩试样进行了实验研究。并且对砂岩、泥岩的力学特性、声发射计数和累计计数以及声发射序列的分形特征进行了对比研究。研究结果表明:砂岩发生的是脆性破坏,泥岩发生的是塑性破坏。脆性破坏岩石的应力-应变过程可分为三个阶段:初始压密阶段、线弹性阶段和塑性破坏阶段,塑性破坏岩石可分为四个阶段:初始压密阶段、线弹性阶段、塑性破坏阶段和残余应力阶段。在初始压密阶段、线弹性阶段和塑性破坏阶段中脆性破坏岩石的声发射累计计数平均增长率要比塑性破坏的高。脆性破坏和塑性破坏岩石的声发射序列都具有分形特征,分形维值在岩石破坏前会出现突降现象,但是塑性破坏岩石出现突降现象的时间要比脆性破坏的长很多。

For researching acoustic emission and fractal characteristics of different damage types of rock under uniaxial compression, a group of testing is carried out to investigate the acoustic emission, fraetal characteristics, acoustic emission count, cumulative count and fractal characteristics of acoustic emission sequence for sandstone and mudstone samples by using rock mechanics test system and acoustic emission instrument. The results show that there is brittle failure happened for sandstone, and plastic failure for mudstone. The stress-strain process of brittle failure rock includes three stages： initial consolidation stage, linear elastic stage and plastic collapse stage. The plastic failure of the rock has four stages ： initial consolidation stage, linear elastic stage, plastic collapse stage and residualstress stage. Average growth rates of acoustic emission cumulative count of brittle failure rock is higher than that of the plastic failure rock in the initial consolidation stage and the linear elastic stage and plastic collapse stage. The rock of brittle failure and plastic failure acoustic emission sequence has the fractal characteristics. The fractal dimension value will jump up before the damage of rock, but the time of fall phenomena in fractal dimension value of the plastic damage of rock is more than that of the brittle failure.