拉张型雁列构造雁列区贯通过程中剪切应变降异常的数值模拟
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摘要
在雁列区贯通之前及过程中,研究雁列构造复杂的相互作用及一些力学量的时空分布规律,对于地震前兆研究具有积极意义.为了延缓岩石材料的破坏过程,在FLAC-3D的应变软化模型中引入了断层和岩石单元的非均质性.为了探索事件的迁移及断层失稳前兆规律,在两条断层的内、外侧岩石上布置若干被监测单元,在标本全场内对大于某一临界值的剪切应变降进行捕捉.研究发现,拉张雁列区内的破坏区不启动于断层端部,这与两条断层的相互影响和作用有关;在雁列区贯通之前,剪切应变降由远及近迁移,雁列区曾一度成为空区,随后空区消失.剪切应变降密集分布在除了雁列区附近的断层附近,反映了大量中等强度的单元发生破坏,而在雁列区贯通之后,剪切应变降总体上回归平静.在同一时刻,不同断层上被监测单元的剪切应变演变规律复杂:同步、不同步共存,这反映了两条非均质断层之间复杂的相互影响和作用.
During and prior to the jog failure,studies of complex interactions among faults and spatiotemporal distributions of some mechanical quantities of echelon faults are especially significant for us to explore seismic precursors.In order to delay the failure process of rock materials,heterogeneities of rock and fault elements are taken into account.Numerical calculations are conducted by use of FLAC-3Dwhere a proposed heterogeneous strain-softening model is included.To investigate migrations of events and unstable precursors or abnormalities,we arrange some monitored rock elements at both sides of two parallel faults constituting an extensional echelon fault,and we also capture larger shear strain decreases within the entire specimen including the echelon fault.It is found that the generated failed zones in the jog can originate from some positions of a fault,rather than its tip,which is related to interactions among two faults.Before the jog failure,shear strain decreases migrate from far away toward the jog. Thus,the jog once becomes vacant.Afterwards,the jog is failed and the gap disappears.Shear strain decreases intensively distribute in the vicinity of a majority of faults except for fault segments close to the jog,suggesting failures of a number of fault elements with moderate strengths. However,after the jog failure,shear strain decreases tend to be silent in total.At the same stress acting on the specimen including an extensional echelon fault,shear strains of different monitored elements at different faults exhibit both synchronized andasynchronized changes.These complex phenomena stem from complex interactions among two heterogeneous faults.
During and prior to the jog failure,studies of complex interactions among faults and spatiotemporal distributions of some mechanical quantities of echelon faults are especially significant for us to explore seismic precursors.In order to delay the failure process of rock materials,heterogeneities of rock and fault elements are taken into account.Numerical calculations are conducted by use of FLAC-3Dwhere a proposed heterogeneous strain-softening model is included.To investigate migrations of events and unstable precursors or abnormalities,we arrange some monitored rock elements at both sides of two parallel faults constituting an extensional echelon fault,and we also capture larger shear strain decreases within the entire specimen including the echelon fault.It is found that the generated failed zones in the jog can originate from some positions of a fault,rather than its tip,which is related to interactions among two faults.Before the jog failure,shear strain decreases migrate from far away toward the jog. Thus,the jog once becomes vacant.Afterwards,the jog is failed and the gap disappears.Shear strain decreases intensively distribute in the vicinity of a majority of faults except for fault segments close to the jog,suggesting failures of a number of fault elements with moderate strengths. However,after the jog failure,shear strain decreases tend to be silent in total.At the same stress acting on the specimen including an extensional echelon fault,shear strains of different monitored elements at different faults exhibit both synchronized andasynchronized changes.These complex phenomena stem from complex interactions among two heterogeneous faults.
引文
Aydin A,Schultz R A.1990.Effect of mechanical interaction on the development of strike-slip faults with echelon patterns[J].J.Struct.Geol.,12(1):123-129.
Barker S L L.2005.Pseudotachylyte-generating faults in Central Otago,New Zealand[J].Tectonophysics,397(3-4):211-223.
Beroza G C,Mikumo T.1996.Short slip duration in dynamic rupture in the presence of heterogeneous fault properties[J].J.Geophys.Res.,101(B10):22449-22460.
Bizzarri A,Cocco M,Andrews D J,et al.2001.Solving the dynamic rupture problem with different numerical approaches and constitutive laws[J].Geophys J Int.,144(3):656-678.
Chen S Y,Liu L Q,Ma S L,et al.2005.An experimental study on variation of b value during deformation of rock samples with different structural models[J].Acta Seismologica Sinica(in Chinese),27(3):317-323.
de Joussineau G,Petit J P,Gauthier B D M.2003.Photoelastic and numerical investigation of stress distributions around fault models under biaxial compressive loading conditions[J].Tectonophysics,363(1-2):19-43.
Du Y J,Aydin A.1995.Shear fracture patterns and connectivity at geometric complexities along strike-slip faults[J].J.Geophys.Res.,100(B9):18093-18102.
Harris R A,Day S M.1999.Dynamic 3D simulations of earthquakes on en echelon faults[J].Geophys.Res.Lett.,26(14):2089-2092.
Hillers G,Ben-Zion Y,Mai P M.2006.Seismicity on a fault controlled by rate-and state-dependent friction with spatial variations of the critical slip distance[J].J.Geophys.Res.,111(B1):B01403,doi:10.1029/2005JB003859.
Jiang H K,Ma S L,Zhang L,et al.2002.Spatio-temporal characteristics of acoustic emission during the deformation of rock samples with compressional and exten-sional en-echelon fault pattern[J].Acta Seismologica Sinica(in Chinese),24(4):385-395.
Liu L Q,Ma J,Wu XQ.1986.An experimental study on the process of deformation and instability for en-echelon faults[J].Acta Seismologica Sinica(in Chinese),8(4):393-403.
Liu P X,Ma J,Liu L Q,et al.2007.An experimental study on variation of thermal fields during the deformation of a compressive en echelon fault set[J].Prog.Nat.Sci.(in Chinese),17(4):454-459.
Ma J,Du Y J,Liu L Q.1986.The instability of en-echelon cracks and its precursors[J].J.Phys.Earth.,34(Supplement):S141-S157.
Ma J,Liu L Q,Ma S L.1999.Fault geometry and departure of precursors from epicenter[J].Earthquake Research in China(in Chinese),15(2):106-115.
Ma J,Ma S L,Liu L Q,et al.2002.Experimental study on patterns of fault interaction[J].Progress in Natural Science(in Chinese),12(5):503-508.
Ma J,Liu L Q,Liu P X,et al.2007.Thermal precursory pattern of fault unstable sliding:an experimental study of en echelon faults[J].Chinese J.Geophys.(in Chinese),50(4):1141-1149.
Ma J,Ma S P,Liu P X,et al.2008.Thermal field indicators for identifying active fault and its instability from laboratory experiments[J].Seismology and Geology(in Chinese),30(2):363-382.363 -382 .Ma J,Ma S P,Liu L Q,et al.2010.Experimental study of thermal and strain fields during de-formation of en echelon faults and its geological implications[J].Geodyn.Tectonophys.,1(1):24-35.
Ma S L,Deng Z H,Ma W T,et al.1995a.Experimental study on evolution of physical field during deformation of en-echelon faults(1)[J].Seismology and Geology(in Chinese),17(4):327-335.
Ma S L,Liu L Q,Deng Z H,et al.1995b.Experimental study on evolution of physical field during deformation of en-echelon faults(2)[J].Seismology and Geology(in Chinese),17(4):336-341.
Ma S L,Jiang H K,Hu X Y,et al.2004.A discussion on mechanism for seismic quiescence before large earthquakes based on experimental results of acoustic emission[J].Seismology and Geology(in Chinese),26(3):426-435.
Ma S L,Chen S Y,Liu P X,et al.2008.Effect of fault jogs on frictional behavior:An experimental study[J].Scientia Sinica Terrae(in Chinese),38(7):842-851.
Ma W T,Ma J,Liu L Q,et al.1995.The characteristics of acoustic emission in en echelon structure[J].Seismology and Geology(in Chinese),17(4):342-348.
Miyatake T.1992.Numerical simulation of three-dimensional faulting processes with heterogeneous rate-and state-dependent friction[J].Tectonophysics,211(1-4):223-232.
Ohlmacher G C,Berendsen P.2005.Kinematics,mechanics,and potential earthquake hazards for faults in Pottawatomie County,Kansas,USA[J].Tectonophysics,396(3-4):227-244.
Olson J E,Pollard D D.1991.The initiation and growth of enéchelonveins[J].J.Struct.Geol.,13(5):595-608.
Palusznya A,Matthib S K.2009.Numerical modeling of discrete multi-crack growth applied to pattern formation in geological brittle media[J].Int.J.Solids Struct.,46(18-19):3383-3397.
Ren Y Q,Liu P X,Ma J,et al.2013.Experimental study on evolution of thermal field of en echelon fault during the metainstability stage[J].Chinese J.Geophys.(in Chinese),56(7):2348-2357,doi:10.6038/cjg20130721.
Segall P,Pollard D D.1980.Mechanics of discontinuous faults[J].J.Geophys.Res.,85(B8):4337-4350.
Sibson R H.1985.Stopping of earthquake ruptures at dilattionalfault jogs[J].Nature,316(6025):248-251.
Smith J V,Yamauchi S.2005.Kinematic interpretation of remnant en-echelon rift segments of the southwestern Japan Sea[J].Tectonophysics,230(3-4):143-150.
Soliva R,Maerten F,Petit J,et al.2010.Field evidences for the role of static friction on fracture orientation in extensional relays along strike-slip faults:Comparison with photoelasticity and 3-D numerical modeling[J].J.Struct.Geol.,32(11):1721-1731.
Swanson M T.1990.Extensional duplexing in the York Cliffs strikeslip fault system,southern coastal Maine[J].J.Struct.Geol.,12(4):499-512.
Talwani P.1999.Fault geometry and earthquakes in continental interiors[J].Tectonophysics,305(1-3):371-379.
Thomas A L,Pollard D D.1993.The geometry of echelon fractures in rock:implications from laboratory and numerical experiments[J].J.Struct.Geol.,15(3-5):323-334.
Wang X B,Ma J,Liu L Q.2010.Numerical simulation of failed zone propagation process and anomalies related to the released energy during a compressive jog intersection[J].J.Mech.Mat.Struct.,5(6):1007-1022.
Wang X B,Ma J,Liu L Q.2012.A comparison of mechanical behavior and frequency-energy relations for two kinds of echelon fault structures through numerical simulation[J].Pure Appl.Geophys.,169(11):1927-1945.
Wang X B,Ma J,Pan Y S.2013a.Numerical simulation of stickslip behaviours of typical faults in biaxial compression based on a frictional-hardening and frictional-softening model[J].Geophys.J.Int.,194(2):1023-1041.
Wang X B,Ma J,Liu L Q.2013b.Numerical simulation of large shear strain drops during jog failure for echelon faults based on a heterogeneous and strain-softening model[J].Tectonophysics,608:667-684.
Wang X B,Gu L,Ma B,et al.2013c.A Frequency-energy method to determine the hazard faults among faults and numerical simulation[J].Progress in Geophysics(in Chinese),28(5):2739-2747,doi:10.6038/pg20130558.
Wang X B,LüJ Q,Ma B,et al.2014.Effects of fault spacing on the deformation,failure process and released energy for the extensional echelon faults:a numerical simulation[J].Progress in Geophysics(in Chinese),29(1):406-411,doi:10.6038/pg20140158.
Zachariasen J,Sieh K.1995.The transfer of slip between two en echelon strike-slip faults:a case study from the 1992Landers earthquake,southern California[J].J.Geophys.Res.,100(B8):15281-15301.
陈顺云,刘力强,马胜利,等.2005.构造活动模式变化对b值影响的实验研究[J].地震学报,27(3):317-323.
蒋海昆,马胜利,张流,等.2002.雁列式断层组合变形过程中的声发射活动特征[J].地震学报,24(4):385-395.
刘力强,马瑾,吴秀泉.1986.雁列式断层变形与失稳过程的实验研究[J].地震学报,8(4):393-403.
刘培洵,马瑾,刘力强,等.2007.压性雁列构造变形过程中热场演化的实验研究[J].自然科学进展,17(4):454-459.
马瑾,刘力强,马胜利.1999.断层几何与前兆偏离[J].中国地震,15(2):106-115.
马瑾,马胜利,刘力强,等.2002.断层相互作用型式的实验研究[J].自然科学进展,12(5):503-508.
马瑾,刘力强,刘培洵,等.2007.断层失稳错动热场前兆模式:雁列断层的实验研究[J].地球物理学报,50(4):1141-1149.
马瑾,马少鹏,刘培洵,等.2008.识别断层活动和失稳的热场标志—实验室的证据[J].地震地质,30(2):363-382.
马胜利,邓志辉,马文涛,等.1995a.雁列式断层变形过程中物理场演化的实验研究(一)[J].地震地质,17(4):327-335.
马胜利,刘力强,邓志辉,等.1995b.雁列式断层变形过程中物理场演化的实验研究(二)[J].地震地质,17(4):336-341.
马胜利,蒋海昆,扈小燕,等.2004.基于声发射实验结果讨论大震前地震活动平静现象的机制[J].地震地质,26(3):426-435.
马胜利,陈顺云,刘培洵,等.2008.断层阶区对滑动行为影响的实验研究[J].中国科学D辑:地球科学,38(7):842-851.
马文涛,马瑾,刘力强,等.1995.雁列断层变形过程中的声发射特征[J].地震地质,17(4):342-348.
任雅琼,刘培洵,马瑾,等.2013.亚失稳阶段雁列断层热场演化的实验研究[J].地球物理学报,56(7):2348-2357,doi:10.6038/cjg20130721.
王学滨,顾路,马冰,等.2013.断层系统中危险断层识别的频次-能量方法及数值模拟[J].地球物理学进展,28(5):2739-2747,doi:10.6038/pg20130558.
王学滨,吕家庆,马冰,等.2014.断层间距对拉张雁列构造破坏过程及能量释放影响的模拟[J].地球物理学进展,29(1):406-411 ,doi:10.6038/pg20140158.
Barker S L L.2005.Pseudotachylyte-generating faults in Central Otago,New Zealand[J].Tectonophysics,397(3-4):211-223.
Beroza G C,Mikumo T.1996.Short slip duration in dynamic rupture in the presence of heterogeneous fault properties[J].J.Geophys.Res.,101(B10):22449-22460.
Bizzarri A,Cocco M,Andrews D J,et al.2001.Solving the dynamic rupture problem with different numerical approaches and constitutive laws[J].Geophys J Int.,144(3):656-678.
Chen S Y,Liu L Q,Ma S L,et al.2005.An experimental study on variation of b value during deformation of rock samples with different structural models[J].Acta Seismologica Sinica(in Chinese),27(3):317-323.
de Joussineau G,Petit J P,Gauthier B D M.2003.Photoelastic and numerical investigation of stress distributions around fault models under biaxial compressive loading conditions[J].Tectonophysics,363(1-2):19-43.
Du Y J,Aydin A.1995.Shear fracture patterns and connectivity at geometric complexities along strike-slip faults[J].J.Geophys.Res.,100(B9):18093-18102.
Harris R A,Day S M.1999.Dynamic 3D simulations of earthquakes on en echelon faults[J].Geophys.Res.Lett.,26(14):2089-2092.
Hillers G,Ben-Zion Y,Mai P M.2006.Seismicity on a fault controlled by rate-and state-dependent friction with spatial variations of the critical slip distance[J].J.Geophys.Res.,111(B1):B01403,doi:10.1029/2005JB003859.
Jiang H K,Ma S L,Zhang L,et al.2002.Spatio-temporal characteristics of acoustic emission during the deformation of rock samples with compressional and exten-sional en-echelon fault pattern[J].Acta Seismologica Sinica(in Chinese),24(4):385-395.
Liu L Q,Ma J,Wu XQ.1986.An experimental study on the process of deformation and instability for en-echelon faults[J].Acta Seismologica Sinica(in Chinese),8(4):393-403.
Liu P X,Ma J,Liu L Q,et al.2007.An experimental study on variation of thermal fields during the deformation of a compressive en echelon fault set[J].Prog.Nat.Sci.(in Chinese),17(4):454-459.
Ma J,Du Y J,Liu L Q.1986.The instability of en-echelon cracks and its precursors[J].J.Phys.Earth.,34(Supplement):S141-S157.
Ma J,Liu L Q,Ma S L.1999.Fault geometry and departure of precursors from epicenter[J].Earthquake Research in China(in Chinese),15(2):106-115.
Ma J,Ma S L,Liu L Q,et al.2002.Experimental study on patterns of fault interaction[J].Progress in Natural Science(in Chinese),12(5):503-508.
Ma J,Liu L Q,Liu P X,et al.2007.Thermal precursory pattern of fault unstable sliding:an experimental study of en echelon faults[J].Chinese J.Geophys.(in Chinese),50(4):1141-1149.
Ma J,Ma S P,Liu P X,et al.2008.Thermal field indicators for identifying active fault and its instability from laboratory experiments[J].Seismology and Geology(in Chinese),30(2):363-382.363 -382 .Ma J,Ma S P,Liu L Q,et al.2010.Experimental study of thermal and strain fields during de-formation of en echelon faults and its geological implications[J].Geodyn.Tectonophys.,1(1):24-35.
Ma S L,Deng Z H,Ma W T,et al.1995a.Experimental study on evolution of physical field during deformation of en-echelon faults(1)[J].Seismology and Geology(in Chinese),17(4):327-335.
Ma S L,Liu L Q,Deng Z H,et al.1995b.Experimental study on evolution of physical field during deformation of en-echelon faults(2)[J].Seismology and Geology(in Chinese),17(4):336-341.
Ma S L,Jiang H K,Hu X Y,et al.2004.A discussion on mechanism for seismic quiescence before large earthquakes based on experimental results of acoustic emission[J].Seismology and Geology(in Chinese),26(3):426-435.
Ma S L,Chen S Y,Liu P X,et al.2008.Effect of fault jogs on frictional behavior:An experimental study[J].Scientia Sinica Terrae(in Chinese),38(7):842-851.
Ma W T,Ma J,Liu L Q,et al.1995.The characteristics of acoustic emission in en echelon structure[J].Seismology and Geology(in Chinese),17(4):342-348.
Miyatake T.1992.Numerical simulation of three-dimensional faulting processes with heterogeneous rate-and state-dependent friction[J].Tectonophysics,211(1-4):223-232.
Ohlmacher G C,Berendsen P.2005.Kinematics,mechanics,and potential earthquake hazards for faults in Pottawatomie County,Kansas,USA[J].Tectonophysics,396(3-4):227-244.
Olson J E,Pollard D D.1991.The initiation and growth of enéchelonveins[J].J.Struct.Geol.,13(5):595-608.
Palusznya A,Matthib S K.2009.Numerical modeling of discrete multi-crack growth applied to pattern formation in geological brittle media[J].Int.J.Solids Struct.,46(18-19):3383-3397.
Ren Y Q,Liu P X,Ma J,et al.2013.Experimental study on evolution of thermal field of en echelon fault during the metainstability stage[J].Chinese J.Geophys.(in Chinese),56(7):2348-2357,doi:10.6038/cjg20130721.
Segall P,Pollard D D.1980.Mechanics of discontinuous faults[J].J.Geophys.Res.,85(B8):4337-4350.
Sibson R H.1985.Stopping of earthquake ruptures at dilattionalfault jogs[J].Nature,316(6025):248-251.
Smith J V,Yamauchi S.2005.Kinematic interpretation of remnant en-echelon rift segments of the southwestern Japan Sea[J].Tectonophysics,230(3-4):143-150.
Soliva R,Maerten F,Petit J,et al.2010.Field evidences for the role of static friction on fracture orientation in extensional relays along strike-slip faults:Comparison with photoelasticity and 3-D numerical modeling[J].J.Struct.Geol.,32(11):1721-1731.
Swanson M T.1990.Extensional duplexing in the York Cliffs strikeslip fault system,southern coastal Maine[J].J.Struct.Geol.,12(4):499-512.
Talwani P.1999.Fault geometry and earthquakes in continental interiors[J].Tectonophysics,305(1-3):371-379.
Thomas A L,Pollard D D.1993.The geometry of echelon fractures in rock:implications from laboratory and numerical experiments[J].J.Struct.Geol.,15(3-5):323-334.
Wang X B,Ma J,Liu L Q.2010.Numerical simulation of failed zone propagation process and anomalies related to the released energy during a compressive jog intersection[J].J.Mech.Mat.Struct.,5(6):1007-1022.
Wang X B,Ma J,Liu L Q.2012.A comparison of mechanical behavior and frequency-energy relations for two kinds of echelon fault structures through numerical simulation[J].Pure Appl.Geophys.,169(11):1927-1945.
Wang X B,Ma J,Pan Y S.2013a.Numerical simulation of stickslip behaviours of typical faults in biaxial compression based on a frictional-hardening and frictional-softening model[J].Geophys.J.Int.,194(2):1023-1041.
Wang X B,Ma J,Liu L Q.2013b.Numerical simulation of large shear strain drops during jog failure for echelon faults based on a heterogeneous and strain-softening model[J].Tectonophysics,608:667-684.
Wang X B,Gu L,Ma B,et al.2013c.A Frequency-energy method to determine the hazard faults among faults and numerical simulation[J].Progress in Geophysics(in Chinese),28(5):2739-2747,doi:10.6038/pg20130558.
Wang X B,LüJ Q,Ma B,et al.2014.Effects of fault spacing on the deformation,failure process and released energy for the extensional echelon faults:a numerical simulation[J].Progress in Geophysics(in Chinese),29(1):406-411,doi:10.6038/pg20140158.
Zachariasen J,Sieh K.1995.The transfer of slip between two en echelon strike-slip faults:a case study from the 1992Landers earthquake,southern California[J].J.Geophys.Res.,100(B8):15281-15301.
陈顺云,刘力强,马胜利,等.2005.构造活动模式变化对b值影响的实验研究[J].地震学报,27(3):317-323.
蒋海昆,马胜利,张流,等.2002.雁列式断层组合变形过程中的声发射活动特征[J].地震学报,24(4):385-395.
刘力强,马瑾,吴秀泉.1986.雁列式断层变形与失稳过程的实验研究[J].地震学报,8(4):393-403.
刘培洵,马瑾,刘力强,等.2007.压性雁列构造变形过程中热场演化的实验研究[J].自然科学进展,17(4):454-459.
马瑾,刘力强,马胜利.1999.断层几何与前兆偏离[J].中国地震,15(2):106-115.
马瑾,马胜利,刘力强,等.2002.断层相互作用型式的实验研究[J].自然科学进展,12(5):503-508.
马瑾,刘力强,刘培洵,等.2007.断层失稳错动热场前兆模式:雁列断层的实验研究[J].地球物理学报,50(4):1141-1149.
马瑾,马少鹏,刘培洵,等.2008.识别断层活动和失稳的热场标志—实验室的证据[J].地震地质,30(2):363-382.
马胜利,邓志辉,马文涛,等.1995a.雁列式断层变形过程中物理场演化的实验研究(一)[J].地震地质,17(4):327-335.
马胜利,刘力强,邓志辉,等.1995b.雁列式断层变形过程中物理场演化的实验研究(二)[J].地震地质,17(4):336-341.
马胜利,蒋海昆,扈小燕,等.2004.基于声发射实验结果讨论大震前地震活动平静现象的机制[J].地震地质,26(3):426-435.
马胜利,陈顺云,刘培洵,等.2008.断层阶区对滑动行为影响的实验研究[J].中国科学D辑:地球科学,38(7):842-851.
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