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Acoustic Emission Prediction of Rock Fracture and Application to Geostress Survey of Kaiser Effect

Author: ChuJun
Tutor: YangYongJie
School: Shandong University of Science and Technology
Course: Engineering Mechanics
Keywords: Rock fracture Uniaxial compression Acoustic emission Kaiser effect Stress relief
CLC: TU452
Type: Master's thesis
Year: 2008
Downloads: 215
Quote: 0
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Abstract


Mine disasters such as cave, water inrush, burst, such as coal and gas outburst occurrence and is closely related to instability and failure of rock and acoustic emission (micro-earthquakes) is a rock before rupture important precursor information given in the experimental indoor rock compressive failure of acoustic emission testing, the use of acoustic emission information to predict rock failure instability for the use of acoustic emission (micro-seismic) monitoring technology forecasting and prevention of rock fracture caused by underground mining disasters has important theoretical and practical significance. Rock test subjects using MTS815.03 servo systems and SDAES-6-type acoustic emission analyzer, 16 coal mine roof on Grange limestone foundation for indoor mechanical properties test, uniaxial compression acoustic emission testing and numerical simulation. Through uniaxial compression deformation and failure of acoustic emission tests and found that compressive deformation and failure process of rock native to its internal fissures compaction, the new generation of cracks, expansion, through such evolution is closely related to its acoustic emission characteristics better reflects the rock deformation and failure and damage evolution. Also verify that the Kaiser effect of acoustic emission point exists only in the rock elastic stage concluded, Kaiser effect point record previously subjected to stresses of rock maximum, this experiment three limestone specimens were memories of the maximum stress that the specimen limit stress by 45.5%, 47.5%, 45.2%. Using RFPA 2D on the destruction and damage evolution of rock deformation characteristics of numerical simulation results and experimental results are basically consistent, numerical simulation of acoustic emission Kaiser effect point of Step 19, a load of 597.4N, memory maximum stress of 48.7% of the ultimate stress of rock. The test parameters of the resulting acoustic emission time series to extract maximum Lyapunov exponent bucket confirmed using acoustic emission parameters describe the evolution of rock compression fracture system in the future trends are not entirely dependent on the initial presentation of the chaotic state, can be predicted. Through the discrete wavelet decomposition coefficients will be different at different stages of rising tone scale launch events, number of negative energy Lipschitz exponent α of the first extreme axial strain corresponding point for determining the Kaiser effect axial strain point, the second extreme axial strain corresponding to breaking point as a predictor of axial strain point, good agreement with the experimental results, this experiment limestone specimen fracture prediction results show that acoustic emission, three specimens of rock fracture prediction axial strain point of time corresponding to the actual burst, respectively, ahead of time than 4 seconds, 5 seconds, 5 seconds, the prediction error between 6% and 10%. While taking advantage of Kaiser effect method and stress relief method tests Tang mouth coal-1000m level roadway GEOSTRESS West Wing, comparative analysis between the results obtained maximum principal stress ratio of 1.07, the intermediate principal stress ratio of 0.83, the minimum principal stress ratio of 0.75, close to both methods the test results. Description Kaiser effect of acoustic emission method used to obtain the rock mass stress test results more reliable, generally meet the project needs.

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CLC: > Industrial Technology > Building Science > Soil mechanics,foundation engineering > Rock ( rock ) mechanics and rock testing > Rock mechanical properties and stress theory
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