矿山动力灾害预警多波多分量微地震监测理论与正反演方法研究

The mining dynamic disasters events, which always cause loss of life and property, are obviously increasing the frequency and intensity with mining expanding and increasing depth. Furthermore, the elements which always cause a sudden disasters threatening on the underground engineering are more complicated. At present, microseism methods which is carry a wide variety of geophysical properties of surrounding rock and rule of mine dynamic disaster were regarded as one of the most promising methods for monitoring mining dynamic disasters. This project will pay close attention on how to make much information by using ambient noise and microseisms signal which is all recorded with microseisms apparatus. With theoretical research method of combining the numerical simulation and model test etc., this project will be focused on following subjects:.1. Studying on the forward modeling and inversion method for underground mine microseisms wave field. .2. Putting some practical methods to separate effective microseisms signal from noise background and making images with all kinds of effective signals..3. Determining the focal mechanism solution of microseisms and anisotropy by using the shear wave splitting analysis method..4. Researching the response characteristic and the propagation rules of microseisms converted wave based on the theory of two phase medium, which are connected with rock stress, fractures, fluids, et al..5. Exploring new options for the focal mechanisms of microseisms by making use of the waveform matching method with first arrival P wave polarities and S/P amplitude ratios..6. Assessing the orientation and consistency of rock fracture development by computing time difference between fast S wave and slow S wave. .In conclusion, the purpose of this project can not only obtain microseisms events information such as frequency and vibration intensity, but also comprehend geophysical properties of surrounding rock fracture. The results of multi-wave multi-component microseism monitoring data inversion will cover forecasting the location, frequency, intensity of microseismic events and analyzing the rock physical properties, fracture state, fluid dynamics et al.. these will provide scientific basses for mining dynamic disaster warning forecast.

随着矿山开采深度增加和采掘范围扩大，动力灾害频度和强度明显增加，成因更加复杂。微震监测可在灾害发生前夕捕捉有效信息及时预测可能的事故，且所记录的矿山环境背景噪声也携带有围岩物性信息。本项目以矿山动力灾害三分量多波微震监测为研究对象，重点开展矿山开采微震多波波场正反演模拟、弱有效波信号提取及噪声层析成像、微震震源机制解确定与横波分裂各向异性分析等研究。探讨微震转换波在裂隙发育及双相介质中的传播规律和响应特征；寻求微震有效信号与背景噪声波场分离最佳途径，构建矿山环境噪声层析成像方法理论；确立基于波形匹配、Ｐ波极性和横纵波振幅比联合反演震源机制解新方法。通过快、慢S波识别及走时残差估算预测岩层断裂形态和地应力分布等。实现微震事件位置、频率、强度预测以及围岩物理特性、裂隙发育状态、流体动态变化和致灾演变规律等的分析，为矿山动力灾害预警预报提供科学依据。

微震监测已成为矿山灾害预警预报的重要手段之一，本项目以矿山动力灾害三分量多波微震监测为研究对象，重点开展了微地震监测方法理论及岩石物理基础研究、微地震正演模拟及矿山扰动微地震响应特征分析、强干扰背景下微震信号识别与初至时间拾取研究以及微地震反演方法及应用研究等。.首先，对现有微震方法进行了分类研究，对比分析了地面、井中以及井-地联合三类微震监测系统的优点和不足。探讨了地震波速度变化的内在本质因素以及速度各向异性的成因。提出了差值法、比值法、比平方根法三种不同的速度各向异性系数定量表征公式。揭示了岩石动静态弹性参数的差异性主要源于岩石速度频散。对表征岩石衰减特性的品质因子Q值参数测试和估算方法进行了系统分类研究，并基于微测井资料提出了一种稳定的地层Q值估算新方法。.其次，基于程函方程实现了水平层状介质微震波射线追踪三维正演模拟。基于声波波动方程实现了微震波有限差分正演模拟。通过正演模拟探讨了岩石破裂诱发产生微震波的传播特征。.第三，对微地震事件初至到时拾取方法进行了研究，对比分析了能量比法、AIC法、多道互换相关法等的优缺点，综合三种不同方法优点，提出一种适用于多道信号初至拾取的能量比-AIC联合拾取新方法。不仅降低了噪声影响，提高了初至拾取效率。.第四，针对矿山微地震事件的时间和空间随机性特点，探讨了地震面波信息提取方法和基于面波频散进行速度层析反演基本方法。对现有震源定位方法进行了系统梳理，对比分析了走时、波形和神经网络三大类定位方法的优缺点。基于传统的走时双差定位原理，提出一种改进的纵横波双差定位新算法，不仅计算简单，速度快，而且有望提高震源定位精度。对比分析了监测检波器数量以及十字型、环型和矩型观测系统对震源定位的影响。探讨了震源强度反演的具体方法。.研究成果对推动矿山微震监测技术发展和促进矿山动力灾害预测精度的提高具有重要的科学意义。