薄互煤层中透射槽波探测断层的正演模拟

Forward simulation of fault detection by transmitting channel wave in thin alternating coal seams

为了研究西南地区矿井薄互煤层中透射槽波探测断层的可行性,选择具有代表性的攀枝花煤业集团某矿为研究对象,根据实际地质资料建立不含夹矸、含3层夹矸、含3层夹矸和断层的3个薄互煤层的地质模型,通过三维弹性波正演模拟分析槽波的波场特征和频散特征,总结振幅衰减系数成像在薄互煤层中槽波探测断层发育位置及延展方向的有效性;并结合实际应用,探讨了透射槽波在薄互煤层中的传播速度及频散特征,以及断层、夹矸对槽波传播的影响。结果表明:薄互煤层中透射槽波探测,断层在影响薄互煤层槽波传播中占主导作用;0.5 m以下夹矸对槽波的发育和能量成像影响不大;在煤厚相同的情况下,含夹矸层状模型相比不含夹矸层状模型的槽波主频低,槽波对煤厚2 m、夹矸厚度0.5 m以下的薄互煤层能够进行比较准确的探测。透射槽波可在薄互煤层中探测断距大于1/2煤厚的断层位置、走向及延展长度,可为西南地区薄互煤层中构造探查提供参考。

In order to study the feasibility of the fault detection by transmitting channel wave in thin alternating coal seams of southwestern region,a representative area was selected,and a coal mine in Panzhihua Coal Industry Group was selected as the research object.A three-dimensional geological model with three alternating coal seams containing three partings,three partings and faults and without parting was established based on actual geological data.Through the forward simulation and analysis of the characteristics of the wave field and the frequency dispersion of the channel waves of the three dimensional elastic wave,the validity of the amplitude attenuation coefficient imaging in the channel wave detection of the development location and the extension direction of the faults in the thin alternating coal seams was summarized,and combined with the actual application,the propagation velocity,the frequency dispersion characteristics,the influence of the faults and the partings on the propagation of the transmitting channel waves in the thin alternating coal seams were discussed.The results indicated that for the detection of the transmitting channel waves in the thin alternating coal seams,the faults plaid a leading role in the influence on the propagation of the transmitting channel waves in thin alternating coal seams,a parting of less than 0.5 m had little influence on the development and energy imaging of the channel waves,in the case of the same thickness of the coal seams,the dominant frequency of the model with a parting was lower than that of the model without parting,the channel waves can detect relatively accurately the thin alternating coal seams of 2 m thick and with a parting of less than 0.5 m.the research indicate that the transmitting channel waves can detect the location,strike and extension of a fault with the throw bigger chan 1/2 thickness of the coal seam in the thin alternating coal seams,provide reference for the detection of the structures in the thin alternating coal seams in the southwestern region.