Experiment on damage and failure evolution law of coal rock mass
In order to study the damage and failure characteristics of coal and rock mass,the statistical tests of surface dam-age of coal and rock samples under unidirectional loading were carried out with prepared standard briquette samples,the damage evolution of coal and rock mass is studied by digital image technology,and the relationship between speckle dam-age,instantaneous strain,strain change and damage is analyzed.The results show that the damage process of specimen sur-face is divided into four stages:compaction stage,elastic deformation stage,peak stress stage and post-peak failure stage.Based on the analysis of the fissures caused by three types of coal sample damage,it is found that the law of strain increasing along x,y and xy directions is similar,the changes along y direction and xy direction are not obvious,but the changes along x direction are obvious and close to the increasing trend of damage,it is indicated that the strain change along x direction is the main factor of coal sample damage,and the increase of damage accumulation in different development stages leads to the different development degree of fissures,and finally forms the different damage types of coal sample surface.
coal and rock massdamage and failurestress variationstrain variationfracture development
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