基于互相关成像条件的隧道地震波逆时偏移处理
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摘要
目前关于隧道地震反射波超前预报的研究主要集中于波场正演数值模拟或单程波的波动方程偏移,基于双程波波动方程的逆时偏移算法有更高的分辨率和更好的成像效果。将逆时偏移应用于隧道地震反射波成像,通过建立理论的断层、低速夹层、不同倾角地质界面等地质模型进行数值模拟,研究隧道地震超前预报问题。基于声波方程,进行波场逆时延拓的偏移成像,采用交错网格有限差分法,利用互相关成像条件并压制噪音干扰,实现了二维隧道逆时偏移成像。通过建立模型进行偏移的数值试算分析结果表明:采用相关时间成像条件,并对逆时延拓过程中反射波采用特征值法压制,对比激励时间成像条件效果更好,基于交错网格高阶有限差分法的逆时偏移应用于隧道地质超前预报能够对地质界面进行精确成像。
Most researches on numerical simulation of tunnel seismic reflecting wave prediction focus on forward modeling of wave field or migration of one-way wave equation; however reverse time migration based on two-way wave equation has better resolution and imaging effects. Reverse time migration algorithm is applied to tunnel seismic reflection wave imaging by establishing several geological models for fault,weak interlayer and tilted interfaces. Migration imaging is realized by reverse time extension for wave field based on acoustic wave equation. By the staggered grid finite-difference algorithm and using cross-correlation imaging condition to avoid the unwanted artifacts,we realize 2D reverse time migration imaging for a tunnel. Numerical examples show that the eigenvalue is useful in suppressing artifacts in reflected wave and the more accurate image can be obtained by cross-correlation imaging condition,compared with excitation time imaging. In tunnel advanced geological forecast,reverse time migration based on staggered grid finite-difference algorithm can produce fine images for geological interface.
Most researches on numerical simulation of tunnel seismic reflecting wave prediction focus on forward modeling of wave field or migration of one-way wave equation; however reverse time migration based on two-way wave equation has better resolution and imaging effects. Reverse time migration algorithm is applied to tunnel seismic reflection wave imaging by establishing several geological models for fault,weak interlayer and tilted interfaces. Migration imaging is realized by reverse time extension for wave field based on acoustic wave equation. By the staggered grid finite-difference algorithm and using cross-correlation imaging condition to avoid the unwanted artifacts,we realize 2D reverse time migration imaging for a tunnel. Numerical examples show that the eigenvalue is useful in suppressing artifacts in reflected wave and the more accurate image can be obtained by cross-correlation imaging condition,compared with excitation time imaging. In tunnel advanced geological forecast,reverse time migration based on staggered grid finite-difference algorithm can produce fine images for geological interface.
引文
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[6]刘云祯.TGP隧道地震预报系统与预报技术探讨[J].物探与化探,2009,33(2):170-177.
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[8]赵永贵.国内外隧道超前预报技术评析与推介[J].地球物理学进展,2007,22(4):1334-1352.
[9]鲁光银,熊瑛,朱自强.隧道反射波超前探测有限差分正演模拟与偏移处理[J].中南大学学报:自然科学版,2011,42(1):136-141.
[10]刘江平,程飞,范承余,等.基于隧道空间全波场二维数值模拟与特征分析[J].岩土工程学报,2012,34(9):1706-1711.
[11]熊金良,李国发,王濮,等.地震波走时计算的逆风差分算法[J].物探化探计算技术,2004,26(4):295-298.
[12]董良国,马在田,曹景忠.一阶弹性波方程交错网格高阶差分法稳定性研究[J].地球物理学报,2000,43(6):856-864.
[13]张大洲.井间地震弹性波逆时偏移成像研究[D].武汉:中国地质大学(武汉),2009.
[2]钟世航.陆地声纳法的原理及其在铁路地质勘测和隧道施工中的应用[J].中国铁道科学,1995,16(4):48-55.
[3]Dickmann T,Sander B.Drivage concurrent tunnel seismicprediction[J].Felsbau-rock and Soil Engineering,1996,14(1):406-411.
[4]Neil D,Haramy K,Hanson D,et al.Tomography to evaluate siteconditions during tunneling[C]∥3rd National Conference of theGeo-Institute,American Society of Civil Engineers.Geotechnical Special Publication,1999:13-17.
[5]Zhao Y G,Jiang H,Zhao X P.Tunnel seismic tomographymethod for geological prediction and its application[J].Applied Geophysics,2006,3(2):69-74.
[6]刘云祯.TGP隧道地震预报系统与预报技术探讨[J].物探与化探,2009,33(2):170-177.
[7]宋先海,顾汉明,肖伯勋.我国隧道地质超前预报技术述评[J].地球物理学进展,2006,21(2):605-613.
[8]赵永贵.国内外隧道超前预报技术评析与推介[J].地球物理学进展,2007,22(4):1334-1352.
[9]鲁光银,熊瑛,朱自强.隧道反射波超前探测有限差分正演模拟与偏移处理[J].中南大学学报:自然科学版,2011,42(1):136-141.
[10]刘江平,程飞,范承余,等.基于隧道空间全波场二维数值模拟与特征分析[J].岩土工程学报,2012,34(9):1706-1711.
[11]熊金良,李国发,王濮,等.地震波走时计算的逆风差分算法[J].物探化探计算技术,2004,26(4):295-298.
[12]董良国,马在田,曹景忠.一阶弹性波方程交错网格高阶差分法稳定性研究[J].地球物理学报,2000,43(6):856-864.
[13]张大洲.井间地震弹性波逆时偏移成像研究[D].武汉:中国地质大学(武汉),2009.