Study On Precursory Law Prior To Rock Failure Based On Acoustic Emission Time Order

Both of the complex geological conditions and the huge amount of rock engineering construction make China one of the countries that suffer from the most serious engineering geological disasters in the world. In order to reduce the personnel and property losses caused by the engineering geological disasters, the accuracy of rock mass stability assessment and engineering geological disaster forecast must be improved. It is more difficult to assess the rock mass stability by theory methods than field monitoring methods, due to the complexity of rock mass nature and geological environment. Therefore, the study of the relationship between monitoring data and the change of surrounding rock stability is of great importance in disaster prevention, guaranteeing production safety and reducing personnel and property losses.In this paper, the change law of acoustic emission (AE) monitoring information in the rock failure process was studied. Then, a rock stability assessment method was established based on the change law. Lastly, the assessment method was applied to the crown pillar in the Shirengou iron mine. The work in the paper can be summarized as follows:1. The AE tests were conducted on altered granite gneiss under the condition of uniaxial compression. By analyzing the change law of AE hit parameters with time, the time order of abnormal change phenomena of hit parameters, and the relationship between the time order and crack evolution stages were determined.2. Based on the change law of wave velocity with stress under the condition of uniaxial compression, the relationship model of stress-wave velocity was constructed. Then, the model was substituted into location algorithm and the AE event location under the changing wave velocity condition was realized.3. Based on the AE location algorithm, the spatio-temporal evolution law of AE events was analyzed. The time order of AE events distribution phenomena and the relationship between the time order and crack evolution stages were determined.4. By conjoint analysis of the hit parameters change law and the event distribution phenomena, the general time order of AE phenomena were determined. Based on the relationship between the general time order and crack evolution stages, a rock stability assessment method can be established and the stability of rock can be reasonably assessed by the method.5. The microseismic data of the Shirengou iron mine were analyzed by the rock stability assessment method and the stability of’a crown pillar was assessed. The assessment results were also reasonable.