隧道突涌水防突结构微震响应初至拾取方法研究

Micro-seismic First Arrival Pickup Methods of Tunnel Water Inrush Prevention Structure

微震监测技术可通过对防突结构微震事件活动的监测实现对突涌水灾害时空演化过程的评价,而微震信号P波初至的精确拾取是突涌水通道活动精准定位的前提。为了实现突涌水过程中微震信号P波初至的精确拾取,提出能量分析拾取法,基于单自由度振动体系(SDOF)将突涌水微震事件引起的质点加速度运动记录进行能量域转化,使得时间序列中的波至特征在体系输入能、阻尼耗能及弹性动能序列上得到凸显,以此实现P波初至的精准识别,提高定位精度。对比分析不同信噪比微震信号,验证了该方法对于低信噪比的微震信号仍具有明显特征响应。通过构建震源定位双曲线模型,进行STA/LTA的2种拾取方法误差验证。实例显示,定位误差分布范围从STA/LTA的13.3 m缩窄至基于能量分析拾取法的7.8 m。结果表明:该拾取方法优于STA/LTA,能够在无预设阈值的情况下完成波动初至的拾取,避免了预设阈值的人为误差,具有更好的误差控制。

Micro-seismic monitoring technology can realize the evaluation of the temporal and spatial evolution process of water inrush disaster by monitoring the micro-seismic event of the inrush prevention structure,and the accurate acquisition of the first P wave of micro-seismic signal is the premise of the accurate location of water inrush channel activities.In order to accurately pick up the first arrival of P wave of micro-seismic signal in the process of water inrush,the acceleration motion records of particle caused by water inrush micro-seismic events are transformed into energy domain based on SDOF,so that the characteristics of wave arrival in time series are highlighted in the input energy,damping energy consumption and elastic kinetic energy series of the system,so as to realize the accurate identification of the first arrival of P wave and improve the efficiency of the system positioning accuracy.By comparing and analyzing micro-seismic signals with different signal noise ratio,it is verified that the method still has obvious characteristic response to micro-seismic signals with low signal noise ratio.By constructing hyperbolic model of hypocenter location,the error of two pickup methods of STA/LTA is verified.The example shows that the range of location error distribution is narrowed from 13.3 m of STA/LTA to 7.8 m in line with energy analysis pickup method.The results show that the method is superior to STA/LTA in that it can pick up the first arrival of the wave without preset threshold value,which can avoid the artificial error of presett hreshold value and have better error control.