岩石破裂的声发射前兆现象及其显现机理

Forecasting rock failure by acoustic emission (AE) precursory phenomena is a hot issue in the field of rock mechanics in recent years. But due to the complexity of the AE precursor phenomena, the issue is still not solved very well. The project is based on the academic point of view that the essence of rock failure is the process of crack initiation, extension, and evolving into the macroscopic crack. Firstly, the AE precursory phenomena are investigated by laboratory experiments. Combined with the moment tensor analysis, the theory of geophysics, the scanning electron microscope (SEM) and the digital image processing technology, a quantitative relationship between AE data and geometric parameters of cracks is established. Then, construct a numerical model and continuously modify it until the simulation of the damage is in accordance with the crack development. Based on a lot of AE data and the damage simulation results, a statistical relationship between damage parameters and AE data can be found and the complexity of AE precursory phenomena and its internal mechanism can be explained from the mechanics standpoint. At last, combined with the actual working condition another numerical model can be constructed. Based on the relationship between damage parameters and AE data, the development trend of crack and monitoring data can be predicted by the damage simulation results, which is helpful to improving the accuracy of the rock failure forecast results.

利用声发射前兆现象预报岩石破裂是近些年岩石力学领域的热点问题，但由于声发射前兆现象复杂多变的显现形式，这一问题仍旧没有得到很好的解决。本项目从“岩石破裂的实质是微裂纹萌生、扩展直至形成宏观裂纹的过程”这一学术观点出发，首先，通过室内实验研究岩石破裂的声发射前兆现象，结合矩张量分析、地球物理学理论、扫描电子显微镜以及数字图像处理技术建立声发射数据与裂纹几何参数间的函数关系。然后，结合损伤本构关系计算并不断修正数值模型直至模拟的损伤过程可以再现岩石内部裂纹的发展过程。基于大量的声发射实测数据及损伤模拟结果，建立声发射参数及损伤变量间的统计关联性，进而利用损伤力学理论揭示声发射前兆现象的显现机理。最后，基于实际工况建立数值模型，结合声发射参数与损伤变量间的关系，通过模拟实际工况的损伤场对裂纹及监测数据的发展趋势进行预测，帮助提高岩石破坏预报结果的准确率。

随着矿山开采强度的加大，采动诱发的冒顶、岩爆、突水等矿山灾害日趋严重。尽管矿山监测监控系统的建立使得矿山生产的信息化水平不断提高，但现有的理论模型和数值计算方法难以正确反映围岩的实际地压显现过程，灾害监测预警与防控仍然是制约矿山安全开采的技术难题。本项目以此背景，从“岩石破裂的实质是微裂纹萌生、扩展直至形成宏观裂纹的过程”这一学术观点出发，结合室内实验、理论推导、数值模拟与现场监测等手段，对岩石破裂的声发射前兆现象及其显现机理这一课题进行了深入研究。理论上，推导了声发射数据与新生剪切裂纹几何参数间的量化关系，建立了基于声发射监测数据驱动的弹脆性损伤本构模型，结合数值模拟分析了荷载作用下岩石中破裂面、应力场、应变场的时空演化规律，揭示了岩石声发射前兆现象出现的力学机理。技术方法上，提出了适用于单轴传感器及不同破裂机制的声发射能量计算方法，建立了实际监测与数值模拟相结合的岩石破坏预测方法，为岩石的破坏模式及矿山围岩损伤发展趋势的预测提供了新的技术手段。工程应用上，针对石人沟铁矿及弓长岭铁矿空区围岩稳定性评价实际问题，基于微震监测数据对岩体内新生裂纹及由此引起的岩体力学参数劣化进行时空表征，结合实际监测与数值模拟对工程岩体的破坏进行分析预测，把握矿山围岩各区域的损伤发展趋势、稳定状态，为地质灾害的预报预警奠定基础。