全光纤微震监测技术在底板突水监测中的应用研究

Application research of all fiber optic microseismic monitoring technology in monitoring water inrush from floor

目前国内的光纤微震监测系统多是基于光学光栅传感技术,而光纤光栅波长解调限制了系统检测频率与灵敏度,且长时间、连续不间断的微震监测成功案例较少。针对上述问题,提出了一种新型全光纤微震监测系统。以潘二煤矿11023工作面回采过程中底板突水监测为工程背景,使用全光纤微震监测系统与ESG微震监测系统进行对比,得出全光纤微震监测系统具有以下优势:记录的波形频谱特征更清晰,表现出高信噪比优势;对扰动深度的监测范围更大,远距离监测效果更好;震源定位结果分布更加合理,更符合工作面实际开采情况。在监测工作面回采全周期内,分析了11023工作面断层异常区底板破坏与微震活动性关系:在断层和煤层变薄异常区附近,微震事件的数量增多、强度增大;工作面初采期间应力集中释放,受采动影响,底板破坏较深;相对大能量事件主要分布在断层异常区的底板,底板破坏深度约为27 m,微震事件在3煤底板60 m以下没有成线或成面聚集的情况,说明裂隙并未扩展,未形成导水通道,工作面安全回采。

Currently,most fiber optic microseismic monitoring systems in China are based on optical grating sensing technology.However,fiber optic grating wavelength demodulation limits the detection frequency and sensitivity of the system,and there are few successful cases of long-term,continuous and uninterrupted microseismic monitoring.In order to solve the above problems,a new type of all fiber microseismic monitoring system is proposed.Taking the monitoring of water inrush from the floor during the mining process of Pan'er Coal Mine 11023 working face as the engineering background,a comparison is made between the all fiber optic microseismic monitoring system and the ESG microseismic monitoring system.It is found that the all fiber optic microseismic monitoring system has the following advantages.The recorded waveform spectrum features are clearer,showing a high signal-to-noise ratio advantage.The monitoring range for disturbance depth is larger,and the remote monitoring effect is better.The distribution of seismic source positioning results is more reasonable and more in line with the actual mining situation of the working face.During the monitoring of the entire mining cycle of the working face,the relationship between the floor failure and microseismic activity in the fault abnormal area of the 11023 working face is analyzed.Near the fault and coal seam thinning abnormal area,the number and intensity of microseismic events increase.During the initial mining period of the working face,stress is concentrated and released.Due to the influence of mining,the floor is severely damaged.Relatively high energy events are mainly distributed in the floor of the fault anomaly area,with a depth of about 27 meters of damage to the floor.Micro seismic events do not form a line or accumulate in a plane below 60 meters of the 3 coal seam floor.It indicates that cracks have not expanded and no water conducting channels have been formed.The working face can be safely mined.