两种加筋土挡墙的动力特性比较及抗震设计建议
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摘要
为分析比较条带式和包裹式加筋土挡墙的地震动力响应特征,开展了两种加筋土挡墙模型的大型振动台试验。结合震害调查的结果,发现砌块式加筋土挡墙在地震作用下的破坏模式主要表现为局部砌块的松动变形,很少会出现整体垮塌的情况。相比条带式加筋土挡墙,包裹式加筋土挡墙在地震作用下产生的变形量要小。在相同地震量级作用下,包裹式加筋土挡墙相应部位的水平加速度放大系数要小于条带式加筋土挡墙,但峰值动土压力却要比条带式加筋土挡墙大,这是因为包裹式加筋土挡墙面板在地震作用下的变形量小,对土体的约束能力强所致。因此,在抗震设防区,特别是是高地震烈度区进行加筋土挡墙的选型时,包裹式加筋土挡墙应作为一种优选结构。分析认为加筋土挡墙的抗震设计除了要进行整体稳定性的验算外,还应注重墙体变形量的控制,加筋土挡墙在地震作用下的最大变形量应小于允许的变形量。为维持线路的正常使用,加筋土挡墙的变形指数应控制在4%以内。若验算得到的变形量超出允许值,可采取增大墙后填土的压实度和增加拉筋长度,以及加厚墙体和降低墙体坡率等措施。
In order to compare the seismic responses of netted and packaged reinforced soil retaining walls,large-scale shaking table tests are performed.Based on the earthquake damage investigation,it is found that the failure modes of the reinforced wall are mainly characterized by loose deformation of local blocks under earthquake,and that the overall collapse is rare.Compared with the netted reinforced soil retaining wall,the packaged one has smaller deformation.Under the same magnitude of earthquake,the acceleration amplificatory coefficient of the packaged reinforced soil retaining wall is smaller than that of the netted one,while the value of horizontal peak dynamic earth pressures of the former is substantially larger than that of the latter.It is because the soil is constrained effectively by the wall plate of the packaged reinforced soil retaining wall.Therefore,for the selection of the reinforced soil retaining wall in earthquake-resistance protection zone,especially the buildings in high earthquake intensity regions,the packaged reinforced soil retaining wall will be an optimal choice.Through analysis,for the aseismic design of flexible walls,while maintaining the integral stability of the reinforced soil retaining wall,local-deformation control should be paid attention to,and its the maximal displacement should be less than the allow able displacement under earthquake.In order to maintain the normal use of the road,the deformation exponent of the reinforced soil retaining wall should be smaller than 4%.If the deformation exceeds the allowable value,measures will be taken including increasing the compaction of filling materials and geogrid length as well as the thickness of the wall,and reducing its wall slope can reduce the displacement.
In order to compare the seismic responses of netted and packaged reinforced soil retaining walls,large-scale shaking table tests are performed.Based on the earthquake damage investigation,it is found that the failure modes of the reinforced wall are mainly characterized by loose deformation of local blocks under earthquake,and that the overall collapse is rare.Compared with the netted reinforced soil retaining wall,the packaged one has smaller deformation.Under the same magnitude of earthquake,the acceleration amplificatory coefficient of the packaged reinforced soil retaining wall is smaller than that of the netted one,while the value of horizontal peak dynamic earth pressures of the former is substantially larger than that of the latter.It is because the soil is constrained effectively by the wall plate of the packaged reinforced soil retaining wall.Therefore,for the selection of the reinforced soil retaining wall in earthquake-resistance protection zone,especially the buildings in high earthquake intensity regions,the packaged reinforced soil retaining wall will be an optimal choice.Through analysis,for the aseismic design of flexible walls,while maintaining the integral stability of the reinforced soil retaining wall,local-deformation control should be paid attention to,and its the maximal displacement should be less than the allow able displacement under earthquake.In order to maintain the normal use of the road,the deformation exponent of the reinforced soil retaining wall should be smaller than 4%.If the deformation exceeds the allowable value,measures will be taken including increasing the compaction of filling materials and geogrid length as well as the thickness of the wall,and reducing its wall slope can reduce the displacement.
引文
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[6]GB50011—2006铁路工程抗震设计规范[S].2006.(GB50011—2006 Code for seismic design of railwayengineering[S].2006.(in Chinese))
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[10]Transit New Zealand.Bridge manual plus amendment No.1[S].Wellington:Transit New Zealand,1995.
[11]KOSEKI J,HAYANO K.Preliminary report on dam age toretaining walls caused by the 1999 Chi-Chi earthquake,Bulletin of ERS[R].Tokyo:Institute of Industrial Science,Univ of Tokyo,2000,33:23–34.
[12]NEWMARK N M.Effects of earthquakes on dams andembankments[J].Géotechnique,1965,15(2):139–160.
[13]CAI Z,BATHURST R J.Seismic response analysis ofgeosynthetic reinforced soil segmental retaining walls byfinite element method[J].Computers and Geotechnics,1995,17(4):523–546.
[14]BATHURST R J,EL-EMAM M M.Facing contribution toseismic response of reduced scale reinforced soil walls[J].Geosynthetics International,2005,12(5):215–238.
[15]HUANG C C,CHOU L H,TATSUOKA F.Seismicdisplacement of geosythetic-reinforced soil modular blockwalls[J].Geosynthetics International,2003,10(1):2–23.
[16]WHITMAN R V,LIAO S.Seismic design of gravity retainingwalls[C]//Proceedings of the 8th World Conference onEarthquake Engineering,San Francisco,Calif,1984:533–540.
[17]张建经,冯君,肖世国.支挡结构抗震设计中的2个关键技术问题[J].西南交通大学学报,2009,44(6):321–325.(ZHANG Jian-jing,FENG Jun,XIAO Shi-guo.Discussionson two key technical problems for seismic design of retainingwall[J].Journal of Southwest Jiaotong University,2009,44(6):321–325.(in Chinese))
[2]MATSUO O,TSUTSUMI T,YOKOYAMA K,et al.Shaking table tests and analyses of geosythetic-reinforcedsoil retaining walls[J].Geosynthetics International,1998,5(1/2):97–126.
[3]SAKAGUCHI M A.Study of the seismic behavior ofgeosynthetic reinforced walls in Japan[J].GeosyntheticsInternational,1996,3(1):13–30.
[4]KOSEKI J,MUNAF Y,TATSUOKA F,et al.Shaking and tilttable tests of geosynthetic-reinforced soil andconventional-type retaining walls[J].GeosyntheticsInternational,1998,5(1/2):73–96.
[5]EL-EMAM M M,BATHURST R J.Experimental design,instrumentation and interpretation of reinforced soil wallresponse using a shaking table[J].International Journal ofPhysical Modelling in Geotechnics,2004,4(4):13–32.
[6]GB50011—2006铁路工程抗震设计规范[S].2006.(GB50011—2006 Code for seismic design of railwayengineering[S].2006.(in Chinese))
[7]JTG/T B02—01—2008公路桥梁抗震设计细则[S].2008(JTG/T B02—01—2008 Guidelines for seismic design ofhighway bridges[S].Beijing:China Communications Press,2008.(in Chinese))
[8]EUROPEAN STANDARD 1998 Eurocode 8:Design ofstructures for earthquake resistance part 5:foundations,retaining structures and geotechnical aspects[S].1998.
[9]日本鉄道構造物の設計基準[S].1998.(Japanese railwayinstallations design standards[S].1998.(in Japanese))
[10]Transit New Zealand.Bridge manual plus amendment No.1[S].Wellington:Transit New Zealand,1995.
[11]KOSEKI J,HAYANO K.Preliminary report on dam age toretaining walls caused by the 1999 Chi-Chi earthquake,Bulletin of ERS[R].Tokyo:Institute of Industrial Science,Univ of Tokyo,2000,33:23–34.
[12]NEWMARK N M.Effects of earthquakes on dams andembankments[J].Géotechnique,1965,15(2):139–160.
[13]CAI Z,BATHURST R J.Seismic response analysis ofgeosynthetic reinforced soil segmental retaining walls byfinite element method[J].Computers and Geotechnics,1995,17(4):523–546.
[14]BATHURST R J,EL-EMAM M M.Facing contribution toseismic response of reduced scale reinforced soil walls[J].Geosynthetics International,2005,12(5):215–238.
[15]HUANG C C,CHOU L H,TATSUOKA F.Seismicdisplacement of geosythetic-reinforced soil modular blockwalls[J].Geosynthetics International,2003,10(1):2–23.
[16]WHITMAN R V,LIAO S.Seismic design of gravity retainingwalls[C]//Proceedings of the 8th World Conference onEarthquake Engineering,San Francisco,Calif,1984:533–540.
[17]张建经,冯君,肖世国.支挡结构抗震设计中的2个关键技术问题[J].西南交通大学学报,2009,44(6):321–325.(ZHANG Jian-jing,FENG Jun,XIAO Shi-guo.Discussionson two key technical problems for seismic design of retainingwall[J].Journal of Southwest Jiaotong University,2009,44(6):321–325.(in Chinese))
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