强震作用下陡倾顺层斜坡倾倒变形机制离心振动台试验
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摘要
陡倾顺层斜坡在静力条件下的稳定性一般较好,但是在"5.12"汶川地震中该类型斜坡却发生了大量的失稳破坏现象,通过现场调查在陡倾软硬相间顺层斜坡中发现了一类特殊的动力变形破坏模式——倾倒变形。在已有认识基础上,以四川汶川县水磨沟陡倾软硬相间顺层斜坡在强震作用下的失稳案例为基础,通过离心振动台试验研究该类型斜坡在强震作用下的倾倒变形机制和动力响应规律特性。研究表明:在斜坡表面,随着高程的增加,加速度放大系数总体表现出先增大、后减小、再增大的节律性变化,在坡高1/3处和坡肩部位动力响应呈现两个峰值。在同一水平高度下,越靠近坡表,加速度放大系数越大,即斜坡岩土体临空面效应较为显著。通过试验揭示该类斜坡失稳机制为:在强震荷载反复作用下,软岩和硬岩产生差异剪切破坏,岩土体沿优势层面下滑受阻,坡脚附近岩土体弯曲隆起,斜坡深层潜在滑面未完全贯通,坡肩震裂松弛岩体在地震的巨大水平惯性力下,向临空面作悬臂梁弯曲倾倒,整个斜坡发生拉裂滑移-下部弯曲-上部倾倒式失稳破坏。
The stability of steep bedding slope is generally better under static force condition, but lots of instable fracture phenomena occurred in this type of slop during "5.12" Wenchuan earthquake. A special dynamic deformation failure mode, toppling deformation, is found in steep soft-hard alternative bedding slope by field investigation. Based on existing knowledge and a failure case, i.e. Shuimogou soft-hard alternative bedding of steep slope in Wenchuan County, Sichuan, the mechanism of toppling deformation and the characteristics of dynamic response of this type of slope under strong earthquake are studied by centrifugal shaking table test. On slope surface, acceleration amplification factor increases first, then decreases, and finally increases with the increase of elevation. The dynamic response shows two peak values at 1/3 of slope height and slope shoulder. At the same horizontal height, the closer to the slope surface, the greater the magnification factor of acceleration, which means that the free face effect of slope rock-soil body ismore significant. Experiment reveals the instability mechanism of this slope: under the repeated actions of strong earthquake loads,differential shear failure occurs between soft rock and hard rock, rock-soil body sliding along the dominant layer is hindered, the rock-soil body nearby slope toe bends and uplifts; the potential sliding surfaces are not connected completely, under the tremendous horizontal inertia force of earthquake, shattered rock stratum at slope shoulder generates cantilever beam bending toppling toward free face, so that the entire slope undergoes tension fracture slippage-lower bending-upper toppling instable fracture.
The stability of steep bedding slope is generally better under static force condition, but lots of instable fracture phenomena occurred in this type of slop during "5.12" Wenchuan earthquake. A special dynamic deformation failure mode, toppling deformation, is found in steep soft-hard alternative bedding slope by field investigation. Based on existing knowledge and a failure case, i.e. Shuimogou soft-hard alternative bedding of steep slope in Wenchuan County, Sichuan, the mechanism of toppling deformation and the characteristics of dynamic response of this type of slope under strong earthquake are studied by centrifugal shaking table test. On slope surface, acceleration amplification factor increases first, then decreases, and finally increases with the increase of elevation. The dynamic response shows two peak values at 1/3 of slope height and slope shoulder. At the same horizontal height, the closer to the slope surface, the greater the magnification factor of acceleration, which means that the free face effect of slope rock-soil body ismore significant. Experiment reveals the instability mechanism of this slope: under the repeated actions of strong earthquake loads,differential shear failure occurs between soft rock and hard rock, rock-soil body sliding along the dominant layer is hindered, the rock-soil body nearby slope toe bends and uplifts; the potential sliding surfaces are not connected completely, under the tremendous horizontal inertia force of earthquake, shattered rock stratum at slope shoulder generates cantilever beam bending toppling toward free face, so that the entire slope undergoes tension fracture slippage-lower bending-upper toppling instable fracture.
引文
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[13]李邵军,KNAPPETT J A,冯夏庭.库水位升降条件下边坡失稳离心模型试验研究[J].岩石力学与工程学报,2008,27(8):1586-1592.LI Shao-jun,KNAPPETT J A,FENG Xia-ting.Centrifugal test on slope instability influenced by rise and fall of reservoir water level[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(8):1586-1592.
[14]李邵军,KNAPPETT J A,冯夏庭,等.模拟库水位变化的抗滑桩加固边坡离心模型试验研究[J].岩石力学与工程学报,2009,28(5):939-946.LI Shao-jun,KNAPPETT J A,FENG Xia-ting,et al.Centrifugal tests on slope reinforcement by anti-sliding piles modelling change of reservoir water level[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(5):939-946.
[15]孙志亮,孔令伟,郭爱国.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[J].岩石力学与工程学报,2017,36(6):1413-1423.SUN Zhi-liang,KONG Ling-wei,GUO Ai-guo.Centrifuge modeling tests on seismic response of lower bedrock deposit slopes before and after reinforced with stabilizing piles[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(6):1413-1423.
[16]邢建营,邢义川,陈祖煜,等.岩质边坡楔形体破坏的离心模型试验方法研究[J].水土保持通报,2005,25(3):15-19.XING Jian-ying,XING Yi-chuan,CHEN Zu-yu,et al.Method research on centrifugal modeling of wedge failure in rocky slope[J].Bulletin of Soil and Water Conservation,2005,25(3):15-19.
[17]于玉贞,邓丽军.抗滑桩加固边坡地震响应离心模型试验[J].岩土工程学报,2007,29(9):1320-1323.YU Yu-zhen,DENG Li-jun.Centrifuge model of seismic behavior of slop reinforced by stabilizing pile[J].Chinese Journal of Geotechnical Engineering,2007,29(9):1320-1323.
[18]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):401-414.
[19]李祥龙,唐辉明,王立朝.顺层岩体边坡地震动力破坏离心机试验研究[J].岩石力学与工程学报,2014,33(4):729-736.LI Xiang-long,TANG Hui-ming,WANG Li-chao.Centrifuge modelling tests on dynamic failure of bedding rock slopes[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(4):729-736.
[20]BRANDENBERG S J,BOULANGER R W,KUTTER BL,et al.Behavior of pile foundations in laterally spreading ground during centrifuge tests[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(11):1378-1391.
[21]SCHOFIELD A N.Cambridge geotechnical centrifuge operation[J].Geotechnique,1980,30(3):227-268.
[22]袁宗盼,陈新明,袁媛,等.地质力学模型相似材料配比的正交试验研究[J].防灾减灾工程学报,2014,34(2):197-202.YUAN Zong-pan,CHEN Xin-ming,YUAN Yuan,et al.Study on ratio of similar material of geomechanical model based on orthogonal test[J].Journal of Disaster Prevention and Mitigation Engineering,2014,34(2):197-202.
[23]左保成,陈从新,刘才华,等.相似材料试验研究[J].岩土力学,2004,25(11):1805-1808.ZUO Bao-cheng,CHEN Cong-xin,LIU Cai-hua,et al.Research on similar material experiment[J].Rock and Soil Mechanics,2004,25(11):1805-1808.
[24]李振生,巨能攀,侯伟龙,等.陡倾层状岩质边坡动力响应大型振动台模型试验研究[J].工程地质学报,2012,20(2):242-248.LI Zhen-sheng,JU Neng-pan,HOU Wei-long,et al.Large-scale shaking table model tests for dynamic response of steep stratified rock slopes[J].Journal of Engineering Geology,2012,20(2):242-248.
[2]黄润秋,张伟锋,裴向军.大光包滑坡工程地质研究[J].工程地质学报,2014,22(4):557-585.HUANG Run-qiu,ZHANG Wei-feng,PEI Xiang-jun.Engineering geological study on Daguangbao landslide[J].Journal of Engineering Geology,2014,22(4):557-585.
[3]王运生,徐鸿彪,罗永红,等.地震高位滑坡形成条件及抛射运动程式研究[J].岩石力学与工程学报,2009,28(11):2360-2368.WANG Yun-sheng,XU Hong-biao,LUO Yong-hong,et al.Study of formation conditions and toss motion program of high landslides induced by earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(11):2360-2368.
[4]黄润秋,李果,巨能攀.层状岩体斜坡强震动力响应的振动台试验[J].岩石力学与工程学报,2013,32(5):865-875.HUANG Run-qiu,LI Guo,JU Neng-pan.Shaking table test on strong earthquake response of stratified rock slopes[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(5):865-875.
[5]黄润秋.汶川8.0级地震触发崩滑灾害机制及地质力学模式[J].岩石力学与工程学报,2009,28(6):1239-1249.HUANG Run-qiu.Mechanics and geomechanical modes of landslide hazards triggered by Wenchuan 8.0earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1239-1249.
[6]许强,黄润秋.5.12汶川大地震诱发大型崩滑灾害动力特征初探[J].工程地质学报,2008,16(6):721-730.XU Qiang,HUANG Run-qiu.Kinetic characteristics of large landslides triggered by May 12th Wenchuan earthquake[J].Journal of Engineering Geology,2008,16(6):721-730.
[7]祁生文,伍法权,严福章,等.岩质边坡动力反应分析[M].北京:科学出版社,2007.QI Sheng-wen,WU Fa-quan,YAN Fu-zhang,et al.Dynamic response analysis of rock slope[M].Beijing:Science Press,2007.
[8]罗刚,胡卸文,顾成状.强震作用下顺层岩质斜坡动力失稳机制及启动速度研究[J].岩土力学,2013,34(2):483-490.LUO Gang,HU Xie-wen,GU Cheng-zhuang.Study of kinetic failure mechanism and starting velocity of consequent rock slopes under strong earthquake[J].Rock and Soil Mechanics,2013,34(2):483-490.
[9]董金玉,杨国香,伍法权,等.地震作用下顺层岩质边坡动力响应和破坏模式大型振动台试验研究[J].岩土力学,2011,32(10):2977-2982.DONG Jin-yu,YANG Guo-xiang,WU Fa-quan,et al.The large-scale shaking table test study of dynamic response and failure mode of bedding rock slope under earthquake[J].Rock and Soil Mechanics,2011,32(10):2977-2982.
[10]艾畅,冯春,李世海,等.地震作用下顺层岩质边坡动力响应的试验研究[J].岩石力学与工程学报,2010,29(9):1825-1832.AI Chang,FENG Chun,LI Shi-hai,et al.Experimental research on dynamic response of consequent rock slope under seismic loading[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(9):1825-1832.
[11]贾俊,黄润秋,巨能攀,等.强震作用下陡倾顺层岩质边坡失稳机制研究[J].工程地质学报,2010,18(增刊):475-481.JIA Jun,HUANG Run-qiu,JU Neng-pan,et al.Study on collapsing and sliding failure mechanism of steep bedding rock slope triggered by strong earthquake[J].Journal of Engineering Geology,2010,18(Supp.):475-481.
[12]巨能攀,李龙起,黄润秋.陡倾顺层斜坡动力失稳机理分析[J].工程科学与技术,2018,50(3):54-66.JU Neng-pan,LI Long-qi,HUANG Run-qiu.Dynamic failure mechanism study of steep bedding rock slope[J].Advanced Engineering Science,2018,50(3):54-66.
[13]李邵军,KNAPPETT J A,冯夏庭.库水位升降条件下边坡失稳离心模型试验研究[J].岩石力学与工程学报,2008,27(8):1586-1592.LI Shao-jun,KNAPPETT J A,FENG Xia-ting.Centrifugal test on slope instability influenced by rise and fall of reservoir water level[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(8):1586-1592.
[14]李邵军,KNAPPETT J A,冯夏庭,等.模拟库水位变化的抗滑桩加固边坡离心模型试验研究[J].岩石力学与工程学报,2009,28(5):939-946.LI Shao-jun,KNAPPETT J A,FENG Xia-ting,et al.Centrifugal tests on slope reinforcement by anti-sliding piles modelling change of reservoir water level[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(5):939-946.
[15]孙志亮,孔令伟,郭爱国.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[J].岩石力学与工程学报,2017,36(6):1413-1423.SUN Zhi-liang,KONG Ling-wei,GUO Ai-guo.Centrifuge modeling tests on seismic response of lower bedrock deposit slopes before and after reinforced with stabilizing piles[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(6):1413-1423.
[16]邢建营,邢义川,陈祖煜,等.岩质边坡楔形体破坏的离心模型试验方法研究[J].水土保持通报,2005,25(3):15-19.XING Jian-ying,XING Yi-chuan,CHEN Zu-yu,et al.Method research on centrifugal modeling of wedge failure in rocky slope[J].Bulletin of Soil and Water Conservation,2005,25(3):15-19.
[17]于玉贞,邓丽军.抗滑桩加固边坡地震响应离心模型试验[J].岩土工程学报,2007,29(9):1320-1323.YU Yu-zhen,DENG Li-jun.Centrifuge model of seismic behavior of slop reinforced by stabilizing pile[J].Chinese Journal of Geotechnical Engineering,2007,29(9):1320-1323.
[18]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):401-414.
[19]李祥龙,唐辉明,王立朝.顺层岩体边坡地震动力破坏离心机试验研究[J].岩石力学与工程学报,2014,33(4):729-736.LI Xiang-long,TANG Hui-ming,WANG Li-chao.Centrifuge modelling tests on dynamic failure of bedding rock slopes[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(4):729-736.
[20]BRANDENBERG S J,BOULANGER R W,KUTTER BL,et al.Behavior of pile foundations in laterally spreading ground during centrifuge tests[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(11):1378-1391.
[21]SCHOFIELD A N.Cambridge geotechnical centrifuge operation[J].Geotechnique,1980,30(3):227-268.
[22]袁宗盼,陈新明,袁媛,等.地质力学模型相似材料配比的正交试验研究[J].防灾减灾工程学报,2014,34(2):197-202.YUAN Zong-pan,CHEN Xin-ming,YUAN Yuan,et al.Study on ratio of similar material of geomechanical model based on orthogonal test[J].Journal of Disaster Prevention and Mitigation Engineering,2014,34(2):197-202.
[23]左保成,陈从新,刘才华,等.相似材料试验研究[J].岩土力学,2004,25(11):1805-1808.ZUO Bao-cheng,CHEN Cong-xin,LIU Cai-hua,et al.Research on similar material experiment[J].Rock and Soil Mechanics,2004,25(11):1805-1808.
[24]李振生,巨能攀,侯伟龙,等.陡倾层状岩质边坡动力响应大型振动台模型试验研究[J].工程地质学报,2012,20(2):242-248.LI Zhen-sheng,JU Neng-pan,HOU Wei-long,et al.Large-scale shaking table model tests for dynamic response of steep stratified rock slopes[J].Journal of Engineering Geology,2012,20(2):242-248.