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加卸载响应比(LURR)理论的实验研究   总被引:13,自引:1,他引:13  
利用大尺度岩石试件破坏声发射实验,对加卸载响应比(Load/Unload Response Ratio)理论进行了实验研究。实验采用的加载条件力求能够模拟地下岩石的复杂受力过程。在加载过程中,岩石试件内部出现的损伤用声发射技术进行了记录。实验数据经过分析之后所得的结论与加卸载响应比理论预测的结果相符合。把加卸载响应比值Y的变化情况与声发射事件定位的过程相对比,也可以进一步看出岩石材料内部的损伤发展过程与加卸载响应比Y值的变化具有一致性。而高Y值的异常情况出现,又是在材料发生最终破坏之前,所以,可以用加卸载响应比理论定量地分析岩石试件损伤演化情况,从而对岩石材料的破坏及地震做出预测。实验结果再一次验证了加卸载响应比理论。  相似文献   
2.
A series of acoustic emission (AE) experiments of rock failure have been conducted under cyclic load in tri-axial stress tests. To simulate the hypocenter condition the specimens are loaded by the combined action of a constant stress, intended to simulate the tectonic loading, and a small sinusoidal disturbance stress, analogous to the Earth tide induced by the Sun and the Moon. Each acoustic emission signal can indicate the occurrence time, location and relative magnitude of the damage (micro-crack) in the specimen. The experimental results verified some precursors such as LURR (Load/Unload Response Ratio) and AER (Accelerating Energy Release) before macro-fracture of the samples. A new parameter, the correlation between the AE and the load, has been proposed to describe the loading history. On the eve of some strong earthquakes the correlation between the Benioff strain and the Coulomb failure stress (CFS) decreases, similar to the variation of LURR prior to strong earthquakes.  相似文献   
3.
Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading process of underground rocks. The damages emerging inside the rock samples were recorded by the acoustic emission technique during the loading process. The experimental results were consistent with prediction by LURR theory. Integrating the changing processes of LURR value Y and the location process of acoustic emission events showed agreement between the variation of LURR value Y and the damage evolution inside the rocks. Furthermore, the high value of Y emerged before the complete breakdown of materials. Therefore, the damage evolution of rock specimen can be quantitatively analyzed with LURR theory, thus the failure of the rock materials and the earthquake occurrence may be predicted. The experimental results gave a further verification of LURR theory.  相似文献   
4.
According to the critical point hypothesis (CPH), energy release would accelerate in power law before occurrence of large earthquakes or failure of brittle materials. In the paper, CPH was studied by acoustic emission experiments of large-scale rock samples. Three kinds of rock samples were used in the experiments. The tri-axial loading condition was applied under different loading histories. The released elastic energy (Acoustic emission) was recorded with acoustic emission technique as microcracks emerged and developed inside the rock samples. The experimental results gave a further verification on the CPH. The elastic energy release of rock samples would accelerate before the failure even under different experimental conditions. Primary studies were also made on medium-term earthquake prediction by using accelerating energy release (AER) in the paper. Foundation item: Project of Natural Sciences Foundation of China (10232050), Project of State Key Basic Research (2002CB412706) and Project of Computer Network Information Center, Chinese Academy of Sciences (2002CB412706).  相似文献   
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Introduction Earthquake is a kind of severe natural disaster. In order to predict earthquake effectively, thegeoscientists at home and abroad have carried out a great deal of studies on seismicity. For exam-ple,Willis, (1924) and Tocher (1959) made some early investigations on seismicity before largeearthquake. Chinese geoscientists performed even more studies in this field (CHEN, et al, 1981;HUANG, FENG, 1981; LIU, 1982; LU, 1985; LU, et al, 2001; MA, et al, 1982; MEI, 1960; …  相似文献   
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