Experimental Study On Acoustic Emission And Damage During The Failure Of Rock

In this thesis, the deformation, damage and acoustic emission (AE) of six kinds of rock samples due to uniaxial compression loading have been investigated with the method of a combination of experimental investigation, theoretical analysis and numerical simulation.The experiment of skarn, quartz diorite, marble, siltstone, iron pyrites and serpentinite was first carried out under uniaxial compression load, and at the mean time the AE signal at the process of compression was monitored by AE instrument as well. The comparative investigation of the characteristics of deformation and AE were conducted and the results are presented as followed: 1. The characteristics of rock AE are correlated to the strength, joints, cracks, and the size and hardness of crystalline grain. 2. The sequence of AE can be divided into four phases: beginning phase, tempestuousness phase, drop phase and dreariness phase. The loss and the duration of the phases are correlated to the rock character and flaws in the rock. 3. The AE rate characteristics are not almost concordant with the AE energy rate. 4. Besides the homogeneity, the strength of rock contributes the activity of AE. The higher the strength is, the lower the activity is. 5. There is a dreariness phase before the failure of most kinds of rock. 6. Whether the precursor is obvious is correlated to rock the character, and the precursor of AE rate is more apparent than the precursor of AE energy rate comparatively.On the basis of experiment, the microscopic mechanism of rock failure and theoretical analysis, a two-parameter Weibull statistic model is adopted to specify the evolve of damage. And the two parameters are calibrated with the AE data of the experiment. The modified method for the model is given out after the analysis of the calibration model. It is basic anastomotic between the modified theoretic model and the experiment result, which verifies the Tightness of the model.Finally, the process of damage, failure and AE of rocks under uniaxial compression were simulated by Rock Failure Process Analysis (RFPA) according to varying strength and homogeneity. These simulationresults include: l.With the increase of homogeneity, the nonlinear deformation of rock reduces, brittleness grows gradually, the appearance of AE becomes later, and the energy released by a single AE becomes bigger. 2. The activity of AE becomes more active, and the plasticity becomes more obvious with decreased rock strength. The results of simulation is basic anastomotic with the experiment.