下伏基岩堆积体边坡抗滑桩加固前后地震响应特征离心模型试验
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摘要
为研究抗滑桩加固上覆堆积体——下伏基岩二元结构边坡的抗震机制,开展2组1∶50比尺的离心振动台模型试验,以对比分析下伏基岩堆积体边坡在抗滑排桩加固前后的地震响应特征与抗滑桩的桩身弯矩分布规律。试验时,输入4级加速度峰值连续增大的El Centro波,监测边坡模型坡面与坡体内的加速度响应、坡顶沉降变形以及抗滑桩上静、动弯矩的分布。试验结果显示由于抗滑桩抑制了上覆堆积体的下滑,坡顶的加速度峰值(PGA)放大系数、加速度反应谱以及竖向沉降变形均有不同程度的降低。抗滑桩一方面加固了上覆堆积滑体另一方面在坡体内产生了地震波的反射叠加效应,使得边坡水平响应加速度放大系数出现了桩前增大桩后减小的现象。下伏基岩堆积体边坡坡顶沉降与Arias烈度在抗滑排桩加固前后均具有良好的正相关线性关系。地震荷载作用过程中抗滑桩动力响应弯矩变化幅值明显大于地震作用后的静弯矩增量,且静弯矩与动弯矩变化幅值的分布均在基岩面附近达到峰值,易在基岩面附近造成抗滑桩的破坏,类似工况下抗滑桩的抗震配筋设计应充分考虑这一特点。
In this research,two centrifuge shaking table model tests with the geometric scale of 1∶50 were conducted to study the seismic behaviours of lower bedrock deposit slopes before and after reinforced with stabilizing piles. 4-stage seismic waves(El Centro wave) with the increasing peak acceleration were applied from the bottom of each model. The acceleration response at slope surface and inside,the crest settlements,the distribution characteristics of static and dynamic bending moments were monitored in the process of tests. The recorded data and observations of the centrifuge models showed that the PGA amplification coefficient,the acceleration response spectra and the settlements at slope crest were decreased to some extent when the lower bedrock deposit slope was reinforced with the stabilizing piles. The stabilizing piles improved the seismic performance of upper deposit under earthquake conditions and in the meantime caused the seismic wave reflection effects in slope body,which make slope surface acceleration amplification factor increased along the pile-crest direction but decreased along the pile-toe direction. The relationships between the permanent displacements at slope crest and the Arias intensity of input seismic waves were linear. The changing amplitude of the dynamic bending moment of pile in the earthquake loading process was significantly larger than the increment of static bending moment after seismic excitations. Both the dynamic bending moment and static bending moment of pile reached their peak values near the bedrock surface,where the stabilizing piles most likely been damaged. These features should be fully considered in the aseismic design of stabilizing piles.
In this research,two centrifuge shaking table model tests with the geometric scale of 1∶50 were conducted to study the seismic behaviours of lower bedrock deposit slopes before and after reinforced with stabilizing piles. 4-stage seismic waves(El Centro wave) with the increasing peak acceleration were applied from the bottom of each model. The acceleration response at slope surface and inside,the crest settlements,the distribution characteristics of static and dynamic bending moments were monitored in the process of tests. The recorded data and observations of the centrifuge models showed that the PGA amplification coefficient,the acceleration response spectra and the settlements at slope crest were decreased to some extent when the lower bedrock deposit slope was reinforced with the stabilizing piles. The stabilizing piles improved the seismic performance of upper deposit under earthquake conditions and in the meantime caused the seismic wave reflection effects in slope body,which make slope surface acceleration amplification factor increased along the pile-crest direction but decreased along the pile-toe direction. The relationships between the permanent displacements at slope crest and the Arias intensity of input seismic waves were linear. The changing amplitude of the dynamic bending moment of pile in the earthquake loading process was significantly larger than the increment of static bending moment after seismic excitations. Both the dynamic bending moment and static bending moment of pile reached their peak values near the bedrock surface,where the stabilizing piles most likely been damaged. These features should be fully considered in the aseismic design of stabilizing piles.
引文
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[12]AL-DEFAE A H,KNAPPETT J A.Newmark sliding block model for pile-reinforced slopes under earthquake loading[J].Soil Dynamics and Earthquake Engineering,2015,75:265-278.
[13]WANG L P,ZHANG G.Centrifuge model test study on pile reinforcement behavior of cohesive soil slopes under earthquake conditions[J].Landslides,2014,11(2):213-223.
[14]LI Z,ESCOFFIER S,KOTRONIS P.Centrifuge modeling of batter pile foundations under sinusoidal dynamic excitation[J].Bulletin of Earthquake Engineering,2016,14(3):673-697.
[15]于玉贞,李荣建,李广信,等.抗滑桩静力与动力破坏离心模型试验对比分析[J].岩土工程学报,2008,30(7):1 090-1 093.(YU Yuzhen,LI Rongjian,LI Guangxin,et al.Centrifuge modeling of static and dynamic failure of stabilizing piles in slope[J].Chinese Journal of Geotechnical Engineering,2008,30(7):1 090-1 093.(in Chinese))
[16]陈云敏,韩超,凌道盛,等.ZJU400离心机研制及其振动台性能评价[J].岩土工程学报,2011,33(12):1 887-1 894.(CHEN Yunmin,HAN Chao,LING Daosheng,et al.Development of geotechnical centrifuge ZJU400 and performance assessment of its shaking table system[J].Chinese Journal of Geotechnical Engineering,2011,33(12):1 887-1 894.(in Chinese))
[17]杜延龄,韩连兵.土工离心模型试验技术[M].北京:中国水利水电出版社,2010:84-89.(DU Yanling,HAN Lianbing.Geotechnical centrifuge model test technology[M].Beijing:China Water and Power Press,2010:84-89.(in Chinese))
[18]KOURKOULIS R,GELAGOTI F,ANASTASOPOULOS I,et al.Hybrid method for analysis and design of slope stabilizing piles[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,138(1):1-14.
[19]徐光兴,姚令侃,高召宁,等.边坡动力特性与动力响应的大型振动台模型试验研究[J].岩石力学与工程学报,2008,27(3):624-632.(XU Guangxing,YAO Lingkan,GAO Zhaoning,et al.Large-scale shaking table test study on dynamic characteristics and dynamic responses of slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):624-632.(in Chinese))
[20]孙志亮,孔令伟,郭爱国,等.应力比与含水状态对松散堆积体动力参数及地表反应谱的影响[J].岩土力学,2015,36(10):2 765-2 772.(SUN Zhiliang,KONG Lingwei,GUO Aiguo,et al.Effects of stress ratio and moisture condition of loose deposits on their dynamic parameters and ground response spectrum[J].Rock and Soil Mechanics,2015,36(10):2 765-2 772.(in Chinese))
[21]NEWMARK N M.Effects of earthquakes on dams and embankments[J].Géotechnique,1965,15(2):139-160.
[22]KOURKOULIS R,GELAGOTI F,ANASTASOPOULOS I,et al.Slope stabilizing piles and pile-groups:parametric study and design insights[J].Journal of Geotechnical and Geoenvironmental Engineering,2011,137(7):663-677.
[2]陈红旗,黄润秋,林峰.大型堆积体边坡的空间工程效应研究[J].岩土工程学报,2005,27(3):323-328.(CHEN Hongqi,HUANGRunqiu,LIN Feng.Study on the spatial engineering effect of large accumulation slope[J].Chinese Journal of Geotechnical Engineering,2005,27(3):323-328.(in Chinese))
[3]张健,胡瑞林,李志清.堆积体滑坡抗滑桩所受推力计算及分布特征研究[J].岩土工程学报,2012,34(11):2 005-2 010.(ZHANGJian,HU Ruilin,LI Zhiqing.Distribution laws of thrust of talus slide on anti-sliding piles[J].Chinese Journal of Geotechnical Engineering,2012,34(11):2 005-2 010.(in Chinese))
[4]黄润秋.汶川8.0级地震触发崩滑灾害机制及其地质力学模式[J].岩石力学与工程学报,2009,28(6):1 239-1 249.(HUANG Runqiu.Mechanism and geomechanical modes of landslide hazards triggered by Wenchuan 8.0 earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1 239-1 249.(in Chinese))
[5]吉随旺,唐永建,胡德贵,等.四川省汶川地震灾区干线公路典型震害特征分析[J].岩石力学与工程学报,2009,28(6):1 250-1 260.(JI Suiwang,TANG Yongjian,HU Degui,et al.Analysis of typical seismic damages of highways in Wenchuan earthquake-induced hazard areas in Sichuan province[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1 250-1 260.(in Chinese))
[6]戴自航,徐祥.边坡抗滑桩设计计算的三维有限元法[J].岩石力学与工程学报,2012,31(12):2 572-2 578.(DAI Zihang,XU Xiang.3D finite element method for design computations[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(12):2 572-2 578.(in Chinese))
[7]吴永,何思明,李新坡.地震波作用下抗滑桩的失效机理[J].四川大学学报:工程科学版,2009,41(3):284-288.(WU Yong,HE Siming,LI Xinpo.Failure mechanism of anti-slide pile under seismic wave[J].Journal of Sichuan University:Engineering Science,2009,41(3):284-288.(in Chinese))
[8]ELLIS E A,DURRANI I K,REDDISH D J.Numerical modelling of discrete pile rows for slope stability and generic guidance for design[J].Géotechnique,2010,60(3):185-195.
[9]赖杰,郑颖人,刘云,等.埋入式抗滑桩抗震性能振动台试验与数值分析[J].岩石力学与工程学报,2013,32(增2):4 165-4 173.(LAI Jie,ZHENG Yingren,LIU Yun,et al.Shaking table test for antiseismic behavoir of embedded anti-slide pile and numerical simulation[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(Supp.2):4 165-4 173.(in Chinese))
[10]SMETHURST J A,POWRIE W.Monitoring and analysis of the bending behaviour of discrete piles used to stabilise a railway embankment[J].Géotechnique,2007,57(8):663-677.
[11]AL-DEFAE A H,KNAPPETT J A.Centrifuge modeling of the seismic performance of pile-reinforced slopes[J].Journal of Geotechnical and Geoenvironmental Engineering,2014,140(6):04014014.
[12]AL-DEFAE A H,KNAPPETT J A.Newmark sliding block model for pile-reinforced slopes under earthquake loading[J].Soil Dynamics and Earthquake Engineering,2015,75:265-278.
[13]WANG L P,ZHANG G.Centrifuge model test study on pile reinforcement behavior of cohesive soil slopes under earthquake conditions[J].Landslides,2014,11(2):213-223.
[14]LI Z,ESCOFFIER S,KOTRONIS P.Centrifuge modeling of batter pile foundations under sinusoidal dynamic excitation[J].Bulletin of Earthquake Engineering,2016,14(3):673-697.
[15]于玉贞,李荣建,李广信,等.抗滑桩静力与动力破坏离心模型试验对比分析[J].岩土工程学报,2008,30(7):1 090-1 093.(YU Yuzhen,LI Rongjian,LI Guangxin,et al.Centrifuge modeling of static and dynamic failure of stabilizing piles in slope[J].Chinese Journal of Geotechnical Engineering,2008,30(7):1 090-1 093.(in Chinese))
[16]陈云敏,韩超,凌道盛,等.ZJU400离心机研制及其振动台性能评价[J].岩土工程学报,2011,33(12):1 887-1 894.(CHEN Yunmin,HAN Chao,LING Daosheng,et al.Development of geotechnical centrifuge ZJU400 and performance assessment of its shaking table system[J].Chinese Journal of Geotechnical Engineering,2011,33(12):1 887-1 894.(in Chinese))
[17]杜延龄,韩连兵.土工离心模型试验技术[M].北京:中国水利水电出版社,2010:84-89.(DU Yanling,HAN Lianbing.Geotechnical centrifuge model test technology[M].Beijing:China Water and Power Press,2010:84-89.(in Chinese))
[18]KOURKOULIS R,GELAGOTI F,ANASTASOPOULOS I,et al.Hybrid method for analysis and design of slope stabilizing piles[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,138(1):1-14.
[19]徐光兴,姚令侃,高召宁,等.边坡动力特性与动力响应的大型振动台模型试验研究[J].岩石力学与工程学报,2008,27(3):624-632.(XU Guangxing,YAO Lingkan,GAO Zhaoning,et al.Large-scale shaking table test study on dynamic characteristics and dynamic responses of slope[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):624-632.(in Chinese))
[20]孙志亮,孔令伟,郭爱国,等.应力比与含水状态对松散堆积体动力参数及地表反应谱的影响[J].岩土力学,2015,36(10):2 765-2 772.(SUN Zhiliang,KONG Lingwei,GUO Aiguo,et al.Effects of stress ratio and moisture condition of loose deposits on their dynamic parameters and ground response spectrum[J].Rock and Soil Mechanics,2015,36(10):2 765-2 772.(in Chinese))
[21]NEWMARK N M.Effects of earthquakes on dams and embankments[J].Géotechnique,1965,15(2):139-160.
[22]KOURKOULIS R,GELAGOTI F,ANASTASOPOULOS I,et al.Slope stabilizing piles and pile-groups:parametric study and design insights[J].Journal of Geotechnical and Geoenvironmental Engineering,2011,137(7):663-677.