基于到时差值的微震波异常信号识别方法

延迟信号和外部异常信号严重影响微震震源定位精度，为了对它们进行有效识别，基于震源定位理论和微震台网几何特性，建立震源定位的双曲线和双曲面控制方程，揭示到时不同震源定位方法所确定的震源轨迹是一系列二维平面中的双曲线或三维空间中的双曲面，且双曲线或双曲面的形状和位置与到时差值密切相关。论证传感器观测到时之间存在P波到时差值理论极限和延迟信号到时差值理论极限，根据到时差值、微震台网布设和监测空间几何特征，构建2种理论极限的求解模型，建立到时差值分析表，提出根据观测到时差值和2种到时差值理论极限内在关系识别延迟信号和外部异常信号的全新方法。现场爆破实验表明：基于到时差值的微震波异常信号识别方法能够对延迟信号和外部异常信号进行有效识别，在剔除2种异常信号后的震源定位精度得到极大提高，实现对震源的高精度定位，满足现场微震监测需求。

A METHOD FOR IDENTIFYING OUTLIER SIGNALS FOR MICROSEISMIC EVENT BASED ON ARRIVAL TIME DIFFERENCE

The delayed signals and external outlier signals are two common outliers which seriously affect the accuracy of microseismic source locating. In order to recognize them efficiently，the hyperbolic and hyperboloidal governing equations were obtained based on the theory of microseismic source locating and the geometrical characteristics of network layout. The source paths from different source location methods were found to be a series of hyperbolas on a plane or hyperboloids in a space；and the shape and the position of hyperbolas or hyperboloids were closely related to the time differences of arrival. The study showed that there were theoretical limits of time differences of arrival for P-wave and delayed wave respectively. A model to derive the two type of theoretical limits of time differences of arrival was established on the analysis of the time differences of arrival and the geometrical characteristics of microseismic network and monitoring space. A table of the time differences of arrival for outlier signals analysis was constructed. A novel method was thus put forward for recognizing the delayed signals and external outlier signals. The feasibility and advantages of this method were verified by an in-situ blasting test. The experimental results show that the delayed signals and external outlier signals are identified correctly and effectively by this novel method. The accuracy of microseismic source location is improved greatly after eliminating the outlier signals.