正断层破坏在砂土中传播规律试验模拟
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摘要
断层错动不仅可以引起地震灾害,而且带来的地层永久性变形,对结构物特别是线性构造物,如地下管线,隧道等,造成很大影响,因此,研究断层破坏在上覆土层中传播规律是十分必要的。本文依据正断层砂箱模型试验,对断层在砂土中传播模式,断层在地表的露头位置,断层垂直位移与土体厚度关系等内容进行了分析,并认为:(1)砂土中正断层破裂面不唯一,出现分叉;(2)传至地表所需的断层垂直位移与倾角无关;(3)正断层传播形成三角剪切带,其宽度随断层倾角减小而增大。
Fault movement cannot only cause earthquake,but also bring about permanent deformation in strata.They have great damage to structures,especially linear structures like underground pipelines and tunnels unavoidably.The Kobe earthquake in Japan in 1995 and the Taiwan Chi-Chi earthquake in 1999,the WenChuan earthquake in China in 2008 have all caused to large losses of lives and properties.Active faults are widely distributed in China.Therefore,study on earthquake fault rupture propagation in overlying strata is essential.Many scholars at home and abroad have paid attentions to this subject.Modeling test,centrifuge test and numerical method are used to research the problem.Generally the damages induced by surface rupture are considered as a result of discontinuous deformations of overlying soil resulting in vertical or lateral offset at the surface of soil.However,due to the reason of the complexity of geological and stratigraphic conditions,the limitation of research and field monitoring methods,the question still does not have a clear answer. On the base of sand box,the paper aims to reveal the patterns of fault rupture propagation and location of surface rupture in sandy soil under 1-g modeling test of normal fault.It also studies the relationship between vertical displacement and height of overlying strata.that the following results are found.The failure surfaces of normal fault begin to propagate directly up to the surface regardless to dip angle.Then the following failure surfaces appear.The required vertical displacement when a complete failure surface forms is independent with the dip angle.In the modeling test,the value of D/H comes out to be 4.4%.As many failure planes exist when fault rupture propagates,an apparent triangle shear zone stays between them.At the surface,the width of the triangle shear zone reaches a maximum S.The value of S becomes greater as the dip angle decreases.
Fault movement cannot only cause earthquake,but also bring about permanent deformation in strata.They have great damage to structures,especially linear structures like underground pipelines and tunnels unavoidably.The Kobe earthquake in Japan in 1995 and the Taiwan Chi-Chi earthquake in 1999,the WenChuan earthquake in China in 2008 have all caused to large losses of lives and properties.Active faults are widely distributed in China.Therefore,study on earthquake fault rupture propagation in overlying strata is essential.Many scholars at home and abroad have paid attentions to this subject.Modeling test,centrifuge test and numerical method are used to research the problem.Generally the damages induced by surface rupture are considered as a result of discontinuous deformations of overlying soil resulting in vertical or lateral offset at the surface of soil.However,due to the reason of the complexity of geological and stratigraphic conditions,the limitation of research and field monitoring methods,the question still does not have a clear answer. On the base of sand box,the paper aims to reveal the patterns of fault rupture propagation and location of surface rupture in sandy soil under 1-g modeling test of normal fault.It also studies the relationship between vertical displacement and height of overlying strata.that the following results are found.The failure surfaces of normal fault begin to propagate directly up to the surface regardless to dip angle.Then the following failure surfaces appear.The required vertical displacement when a complete failure surface forms is independent with the dip angle.In the modeling test,the value of D/H comes out to be 4.4%.As many failure planes exist when fault rupture propagates,an apparent triangle shear zone stays between them.At the surface,the width of the triangle shear zone reaches a maximum S.The value of S becomes greater as the dip angle decreases.
引文
[1]刘学增,朱合华.断层在土体中的传播模式及对地下管线的影响[J].力学与实践,2004,26(5):7～13.Liu Xuezeng,Zhu Hehua.Earthquake fault rupture propagation insoil and its effect on pipeline.Mechanics and Engineering,2004,26(5):7～13.
[2]刘学增,滨田政则.活断层破坏在土体中传播的试验研究[J].岩土工程学报,2004,26(3):425～427.Liu Xuezeng,Hamada M.Experiments on rupture propagation ofactive faults in soil.Chinese Journal of Geotechnical Engineering,2004,26(3):425～427.
[3]Bray JD,Seed RB,Seed HB.Earthquake fault rupture propagationthrough soil[J].Journal of Geotechnical Engineering,1994,120(3):543～561.
[4]Bray JD,Seed RB,Seed HB.Analysis of earthquake fault rupturepropagation through cohesive soil[J].Journal of Geotechnical En-gineering,1994,120(3):562～580.
[5]WH Roth,RF Scott,I Austin.Centrifuge modeling of fault propa-gation through alluvial soils[J].Geophysical research letters,1981,8(6):561～564.
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[7]Lee Jea Woo,Hamada.An experimental study on earthquake faultrupture propagation through a sandy soil deposit[J].StructuralEngineering/Earthquake Engineering,2005,22(1):1～13.
[8]郭恩栋,冯启民,薄景山,等.覆盖土层场地地震断裂实验[J].地震工程与工程振动,2001,21(3):145～149.Guo Endong,Feng Qimin,Bo Jingshan.Seismic test of soil siterupture under fault displacements.Earthquake Engineering andEngineering Vibration,2001,21(3):145～149.
[9]杨杰,陈新民,沈建.断层错动在砂土中传播规律的模型试验研究[J].防灾科技学院学报,2011,13(2):18～23.Yang Jie,Chen Xinmin,Shen Jian.Model test research of thefault slip spreading rule in the soil.Journal of Institute of DisasterPrevention,2011,13(2):18～23.
[10]马小君.逆断层黏滑错动对山岭隧道影响的试验研究[D].上海:同济大学,2011.Ma Xiaojun.Experimental Study on the Effect of Stick-Slip Dislo-cation of Thrust Fault to Mountain Tunnel.Shanghai:Tongji Uni-versity,2011.
[11]林亮伦.正断层黏滑错动对山岭隧道影响的试验研究[D].上海:同济大学,2012.Lin Lianglun.Experimental Study on the Effect of Stick-Slip Dis-location of Normal Fault to Mountain Tunnel.Shanghai:TongjiUniversity,2012.
[12]刘学增,林亮伦.75°倾角逆断层黏滑错动对公路隧道影响的模型试验研究[J].岩石力学与工程学报,2011,30(12):2523～2530.Liu Xuezeng,Lin lianglun.Research on model experiment ofeffect of thrust fault with 75°dip angle stick-slip dislocation onhighway tunnel.Chinese Journal of Rock Mechanics and Engi-neering,2011,30(12):2523～2530.
[2]刘学增,滨田政则.活断层破坏在土体中传播的试验研究[J].岩土工程学报,2004,26(3):425～427.Liu Xuezeng,Hamada M.Experiments on rupture propagation ofactive faults in soil.Chinese Journal of Geotechnical Engineering,2004,26(3):425～427.
[3]Bray JD,Seed RB,Seed HB.Earthquake fault rupture propagationthrough soil[J].Journal of Geotechnical Engineering,1994,120(3):543～561.
[4]Bray JD,Seed RB,Seed HB.Analysis of earthquake fault rupturepropagation through cohesive soil[J].Journal of Geotechnical En-gineering,1994,120(3):562～580.
[5]WH Roth,RF Scott,I Austin.Centrifuge modeling of fault propa-gation through alluvial soils[J].Geophysical research letters,1981,8(6):561～564.
[6]WH Roth,G Kalsi,D Papastamatiou.Numerical modeling of faultpropagation in soils[A].Proceeding of the Fourth InternationalConference on Numerical Method in Geomachanics[C].Edmonton,Canada,1982,2:487～494.
[7]Lee Jea Woo,Hamada.An experimental study on earthquake faultrupture propagation through a sandy soil deposit[J].StructuralEngineering/Earthquake Engineering,2005,22(1):1～13.
[8]郭恩栋,冯启民,薄景山,等.覆盖土层场地地震断裂实验[J].地震工程与工程振动,2001,21(3):145～149.Guo Endong,Feng Qimin,Bo Jingshan.Seismic test of soil siterupture under fault displacements.Earthquake Engineering andEngineering Vibration,2001,21(3):145～149.
[9]杨杰,陈新民,沈建.断层错动在砂土中传播规律的模型试验研究[J].防灾科技学院学报,2011,13(2):18～23.Yang Jie,Chen Xinmin,Shen Jian.Model test research of thefault slip spreading rule in the soil.Journal of Institute of DisasterPrevention,2011,13(2):18～23.
[10]马小君.逆断层黏滑错动对山岭隧道影响的试验研究[D].上海:同济大学,2011.Ma Xiaojun.Experimental Study on the Effect of Stick-Slip Dislo-cation of Thrust Fault to Mountain Tunnel.Shanghai:Tongji Uni-versity,2011.
[11]林亮伦.正断层黏滑错动对山岭隧道影响的试验研究[D].上海:同济大学,2012.Lin Lianglun.Experimental Study on the Effect of Stick-Slip Dis-location of Normal Fault to Mountain Tunnel.Shanghai:TongjiUniversity,2012.
[12]刘学增,林亮伦.75°倾角逆断层黏滑错动对公路隧道影响的模型试验研究[J].岩石力学与工程学报,2011,30(12):2523～2530.Liu Xuezeng,Lin lianglun.Research on model experiment ofeffect of thrust fault with 75°dip angle stick-slip dislocation onhighway tunnel.Chinese Journal of Rock Mechanics and Engi-neering,2011,30(12):2523～2530.
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