煤层中断层的透射槽波定量响应特征

Quantitative response characteristics of transmitted in-seam channel wave in coal seam with faults

影响煤炭开采的隐蔽致灾地质因素主要包括:断层、陷落柱、煤层厚度突变以及应力集中区等。准确、定量地查明这些地质异常体,可为安全高效回采提供地质保障,这也是我国煤矿高产高效地质保障系统的核心内容。煤矿安全高效开采,迫切要求能够超前、定量查明小断层、煤层厚度变化、陷落柱、地应力集中区、瓦斯富集带、裂隙发育带等隐蔽致灾地质因素。煤矿井下槽波地震探测技术已在采煤工作面内部隐伏构造探测方面取得了良好的地质效果,但是该技术尚无法实现断层“三要素”(断距、倾角、倾向)的定量判识和煤厚的直接测量,急需开展相关研究以攻克这一技术瓶颈难题。从数值模拟的角度,分析不同煤厚、不同断距的断层分别对Rayleigh透射槽波和Love透射槽波的频散性及能量的影响,进而研究断层断距与透射槽波能量衰减之间的定量关系。研究结果表明:①垂直断层不会影响槽波的频散特征,只对槽波的能量有明显的影响;②模拟显示,即便断层断距大于煤厚,仍然会有相当的槽波能量通过,特别是长波长分量;③在槽波波长与煤厚相近时,相同规格化断距的断层对槽波的衰减量不随槽波波长变化,且Love槽波和Rayleigh槽波衰减量几乎相同;④采用等效Q描述断层对槽波能量的衰减影响时,规格化断距σ与Q呈倒数关系。研究成果可为透射槽波的断层断距定量探测提供理论支持,但此成果仅仅是基于理论模拟得出的,其用于实际勘探时仍需要进一步研究,下一步将研究如何在实际数据中应用本文提出的断距定量关系式实现断层断距的定量探测。

Hidden disaster-causing geological factors affecting coal mining mainly include faults,collapse columns,sudden changes in coal seam thickness,stress concentration areas,etc.Accurately and quantitatively identifying these geological abnormal bodies can provide a geological guarantee for safe and efficient mining,which is also the core content of the high-yield and efficient geological guarantee system of coal mines in China.Safe and efficient production of coal mines urgently requires that the hidden disaster-causing geological factors such as small faults,coal seam thickness changes,collapse columns,in-situ stress concentration areas,gas enrichment zones,fracture development zones,etc.can be identified in advance and quantitatively.The underground channel wave seismic detection technology in coal mines has achieved good geological results in the detection of hidden structures in coal mining faces,but this technology can not realize the quantitative identification of the“three elements”(fault throw,dip angle and inclination)of faults and the direct measurement of coal thickness.It is urgent to carry out relevant research to overcome this technical bottleneck.From the point of view of numerical simulation,this paper analyzes the influence of faults with different coal thickness and fault throw on the dispersion and energy of Rayleigh transmitted channel wave and Love transmitted channel wave,and then studies the quantitative relationship between fault throw and energy attenuation of transmitted channel wave.The results show that:①The vertical faults do not affect the dispersion characteristics of channel waves,but only have a significant impact on the energy of channel waves.②The simulation shows that even if the fault throw is greater than the coal thickness,there will still be considerable channel wave energy passing through,especially the long wavelength component.③When the channel wave wavelength is close to the coal thickness,the attenuation of the channel wave by the fault with the same normalized fault throw does not change with the channel wave length,and the attenuation of Love channel wave and Rayleigh channel wave are almost the same.④When the equivalent q is used to describe the attenuation effect of faults on channel wave energy,the normalized fault distanceσhas an inverse relationship with the square root of Q.The research results in this paper can provide theoretical support for the quantitative detection of fault throw of transmitted channel wave.However,the above results are only based on theoretical simulation,and further research is still needed when they are used in actual exploration.The future research is to study how to apply the quantitative relationship of fault throw proposed in this paper to realize the quantitative detection of fault throw in actual data.