超高路堑边坡治理工程案例研究Ⅰ:边坡失稳机制模拟分析
|
摘要
概要介绍龙岩双永高速公路K227超高路堑边坡的地形地貌、地质条件、变形破坏过程及特征,结合边坡稳定度反分析思路、强度折减法和开挖有限元仿真技术对该边坡变形孕育过程进行模拟分析和定量评估。采用一种基于应力张量差值的增减变化及其变化量的正负分区来确定边坡开挖松弛区的数值方法,解释路堑高边坡开挖卸荷松弛的力学机理;模拟重现了挖方边坡经历稳定性缓慢上升的卸荷回弹阶段、稳定性线性下降的剪切破裂阶段和稳定性急剧下降的失稳破坏阶段的全过程中应力调整、塑性屈服、滑面孕育和变形破坏的演化规律和发展趋势,揭示了边坡由于快速工程开挖扰动,使潜在软弱带充分暴露,并切断坡脚力学支撑,伴随岩土卸荷松弛及强度弱化,产生坡顶岩土张裂变形、深层软弱带剪切蠕动和坡脚沿结构面临空剪出的失稳机制;间歇性降雨入渗的岩土增重及附加水压使滑坡表现出时滑时停的特征;边坡整体处于临界状态,在继续开挖或持续暴雨冲击条件下,可能导致稳定性骤降,从滑动阶段转化为剧滑阶段。最后,对应急抢险对策、治理方案规划及线路调整设想等问题进行讨论与反思,为边坡病害治理提供了理论依据。
In this paper,the topography,landscape and geological conditions, and deformation process and failure characteristics of the super-high cut slope K227 along the expressway from Yongchun to Yongding in City Longyan of China were described. Simulation and quantitative evaluation of the deformation development of the slope were conducted with the back analysis for slope stability,the strength reduction method and the finite element modelling of excavation. A method based on the differential data of stress tensor is proposed to determine the relaxation zone due to excavation and to explain better the mechanism of unloading relaxation due to the excavation of the high cut slope. The numerical simulation faithfully reproduced the process and trending of the stress adjustment,plastic yielding,development of slip surface and deformation at all stages of the slope failure. The slope stability mildly increased in the unloading rebound stage,linearly reduced in the shearing failure stage and abruptly reduced in the instability stage. The numerical results demonstrated that the disturbance due to the fast excavation led to the potential weak layer to be fully exposed and cut off the mechanical support at the toe of the slope. The unloading relaxation and the weakened strength of the rock and soils resulted in the tension crack at the top,the shearing creep of deep weak layer and the shearing along the joints at the toe of the slope. The intermittent rainfall which increased the weight of the rock and soils and the extra pore water pressure caused the slope to slide intermittently. The slope is close to the limit equilibrium state globally and the stability may be abruptly reduced if further excavation or strong rainfall happen. Finally,the discussions and reflections on the emergency and rescue strategy,the planning of slope disaster mitigation methods and route adjustment are also presented.
In this paper,the topography,landscape and geological conditions, and deformation process and failure characteristics of the super-high cut slope K227 along the expressway from Yongchun to Yongding in City Longyan of China were described. Simulation and quantitative evaluation of the deformation development of the slope were conducted with the back analysis for slope stability,the strength reduction method and the finite element modelling of excavation. A method based on the differential data of stress tensor is proposed to determine the relaxation zone due to excavation and to explain better the mechanism of unloading relaxation due to the excavation of the high cut slope. The numerical simulation faithfully reproduced the process and trending of the stress adjustment,plastic yielding,development of slip surface and deformation at all stages of the slope failure. The slope stability mildly increased in the unloading rebound stage,linearly reduced in the shearing failure stage and abruptly reduced in the instability stage. The numerical results demonstrated that the disturbance due to the fast excavation led to the potential weak layer to be fully exposed and cut off the mechanical support at the toe of the slope. The unloading relaxation and the weakened strength of the rock and soils resulted in the tension crack at the top,the shearing creep of deep weak layer and the shearing along the joints at the toe of the slope. The intermittent rainfall which increased the weight of the rock and soils and the extra pore water pressure caused the slope to slide intermittently. The slope is close to the limit equilibrium state globally and the stability may be abruptly reduced if further excavation or strong rainfall happen. Finally,the discussions and reflections on the emergency and rescue strategy,the planning of slope disaster mitigation methods and route adjustment are also presented.
引文
[1]和昆,蒋楚生.云南元磨高速公路路堑高边坡及滑坡整治工程[J].路基工程,2004,(1):49–51.(HE Kun,JIANG Chusheng.High slope and Landslide regulatory engineering in Yunnan Yuanmo expressway[J].Subgrade Engineering,2004,(1):49–51.(in Chinese))
[2]马惠民,王恭先,周德培.山区高速公路高边坡病害防治实例[M].北京:人民交通出版社,2006:5–20.(MA Huimin,WANG Gongxian,ZHOU Depei.Examples of high slope disease control of highways in mountains area[M].Beijing:China Communications Press,2006:5–20.(in Chinese))
[3]SHENG Q,YUE Z Q,LEE C F,et al.Estimating the excavation disturbed zone in the permanent ship lock slopes of the Three Gorges Project,China[J].International Journal of Rock Mechanics and Mining Sciences,2002,39(2):165–184.
[4]黄润秋,林峰,陈德基,等.岩质高边坡卸荷带形成及其工程性状研究[J].工程地质学报,2001,9(3):227–232.(HUANG Runqiu,LIN Feng,CHEN Deji,et al.Formation mechanism of unloading fracture zone of high slope and its engineering behaviors[J].Journal of Engineering Geology,2001,9(3):227–232.(in Chinese))
[5]GRIFFITH D V,LANE P A,Slope stability analysis by finite elements[J].Geotechnique,1999,49(3):387–403.
[6]郑颖人,赵尚毅.有限元强度折减法在土坡与岩坡中的应用[J].岩石力学与工程学报,2004,23(19):3 381–3 388.(ZHENG Yingren,ZHAO Shangyi.Application of strength reduction FEM in soil and rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(19):3 381–3 388.(in Chinese))
[7]肖世国,周德培.开挖边坡松弛区的确定与数值分析方法[J].西南交通大学学报,2003,38(3):318–322.(XIAO Shiguo,ZHOU Depei.Determination and numerical analysis method of relaxation region for cutting slope[J].Journal of Southwest Jiaotong University,2003,38(3):318–322.(in Chinese))
[8]王浩.岩质路堑高边坡设计理论与方法研究[博士学位论文][D].北京:中国铁道科学研究院,2007.(WANG Hao.Study on the design theory and methods for deep cut rock slopes[Ph.D.Thesis][D].Beijing:Chinese Academy of Railway Sciences,2007.(in Chinese))
[9]邓建辉,李焯芬,葛修润.岩石边坡松动区与位移反分析[J].岩石力学与工程学报,2001,20(2):171–174.(DENG Jianhui,LEE C F,GE Xiurun.Disturbed zones and displacement back analysis for rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2001,20(2):171–174.(in Chinese))
[10]赵朝阳,吴平,张德良,等.路堑边坡位移与失稳反分析应用与问题[J].地下空间与工程学报,2005,1(7):1 050–1 057.(ZHAO Chaoyang,WU Ping,ZHANG Deliang,et al.Application and problem of FEM back analysis from displacement and instability in cutting slope[J].Chinese Journal of Underground Space and Engineering,2005,1(7):1 050–1 057.(in Chinese))
[11]叶龙珍,柳侃,黄瑛瑛,等.福建省公路铁路建设的重大工程地质问题[J].工程地质学报,2014,22(增l):195–201.(YE Longzhen,LIU Kan,HUANG Yingying,et al.The major engineering geological problems of railway and highway construction in Fujian Province[J].Journal of Engineering Geology,2014,22(Supp.1):195–201.(in Chinese))
[12]王浩,林一夫,吴栋梁,等.复杂路堑高边坡病害治理效果模糊层次评价[J].工程地质学报,2014,22(5):936–943.(WANG Hao,LIN Yifu,WU Dongliang,et al.Fuzzy hierarchy analysis for treatment effect of complex cutting high slope disease[J].Journal of Engineering Geology,2014,22(5):936–943.(in Chinese))
[13]王恭先,徐峻岭,刘光代,等.滑坡学与滑坡防治技术[M].北京:中国铁道科学出版社,2004:135–139.(WANG Gongxian,XU Junlin,LIU Guangdai,et al.The science and control technology of landslide[M].Beijin:China Railway Science Press,2004:135–139.(in Chinese))
[14]WANG H,LIAO X P.Mechanical characters of relaxing zone of slopes due to excavation[C]//CHEN Z Y,ZHANG J M,LI Z K,et al ed.Proceedings of the 10th International Symposium on Landslides and Engineered Slopes.London:Taylor&Francis Group,2008:501–506.
[15]HOEK E,CARRANZA-TORRES C,CORKUM B.Hoek-Brown failure criterion–2002 edition[C]//HAMMAH R,BAWDEN W F,CURRAN J,et al ed.Proceedings of the North American Rock Mechanics Society NARMS-TAC 2002.Toronto:University of Toronto Press,2002:267–273.
[16]王浩,廖小平.边坡开挖卸荷松弛区的力学性质研究[J].中国地质灾害与防治学报,2007,18(增1):5–10.(WANG Hao,LIAO Xiaoping.Research on the mechanical character of relaxing zone of slopes due to excavation[J].The Chinese Journal of Geological Hazard and Control,2007,18(Supp.1):5–10.(in Chinese))
[17]王浩.福建省永春至永定高速公路龙岩段K227滑坡设计咨询报告[R].福州:福州大学岩土与地下工程研究中心,2010.(WANG Hao.The consulting report for K227 landslide which is in Yongchun to Yongding Expressway Longyan section in Fujian Province design[R].Fuzhou:Geotechnical and Underground Engineering Research Center,Fuzhou University,2010.(in Chinese))
[2]马惠民,王恭先,周德培.山区高速公路高边坡病害防治实例[M].北京:人民交通出版社,2006:5–20.(MA Huimin,WANG Gongxian,ZHOU Depei.Examples of high slope disease control of highways in mountains area[M].Beijing:China Communications Press,2006:5–20.(in Chinese))
[3]SHENG Q,YUE Z Q,LEE C F,et al.Estimating the excavation disturbed zone in the permanent ship lock slopes of the Three Gorges Project,China[J].International Journal of Rock Mechanics and Mining Sciences,2002,39(2):165–184.
[4]黄润秋,林峰,陈德基,等.岩质高边坡卸荷带形成及其工程性状研究[J].工程地质学报,2001,9(3):227–232.(HUANG Runqiu,LIN Feng,CHEN Deji,et al.Formation mechanism of unloading fracture zone of high slope and its engineering behaviors[J].Journal of Engineering Geology,2001,9(3):227–232.(in Chinese))
[5]GRIFFITH D V,LANE P A,Slope stability analysis by finite elements[J].Geotechnique,1999,49(3):387–403.
[6]郑颖人,赵尚毅.有限元强度折减法在土坡与岩坡中的应用[J].岩石力学与工程学报,2004,23(19):3 381–3 388.(ZHENG Yingren,ZHAO Shangyi.Application of strength reduction FEM in soil and rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(19):3 381–3 388.(in Chinese))
[7]肖世国,周德培.开挖边坡松弛区的确定与数值分析方法[J].西南交通大学学报,2003,38(3):318–322.(XIAO Shiguo,ZHOU Depei.Determination and numerical analysis method of relaxation region for cutting slope[J].Journal of Southwest Jiaotong University,2003,38(3):318–322.(in Chinese))
[8]王浩.岩质路堑高边坡设计理论与方法研究[博士学位论文][D].北京:中国铁道科学研究院,2007.(WANG Hao.Study on the design theory and methods for deep cut rock slopes[Ph.D.Thesis][D].Beijing:Chinese Academy of Railway Sciences,2007.(in Chinese))
[9]邓建辉,李焯芬,葛修润.岩石边坡松动区与位移反分析[J].岩石力学与工程学报,2001,20(2):171–174.(DENG Jianhui,LEE C F,GE Xiurun.Disturbed zones and displacement back analysis for rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2001,20(2):171–174.(in Chinese))
[10]赵朝阳,吴平,张德良,等.路堑边坡位移与失稳反分析应用与问题[J].地下空间与工程学报,2005,1(7):1 050–1 057.(ZHAO Chaoyang,WU Ping,ZHANG Deliang,et al.Application and problem of FEM back analysis from displacement and instability in cutting slope[J].Chinese Journal of Underground Space and Engineering,2005,1(7):1 050–1 057.(in Chinese))
[11]叶龙珍,柳侃,黄瑛瑛,等.福建省公路铁路建设的重大工程地质问题[J].工程地质学报,2014,22(增l):195–201.(YE Longzhen,LIU Kan,HUANG Yingying,et al.The major engineering geological problems of railway and highway construction in Fujian Province[J].Journal of Engineering Geology,2014,22(Supp.1):195–201.(in Chinese))
[12]王浩,林一夫,吴栋梁,等.复杂路堑高边坡病害治理效果模糊层次评价[J].工程地质学报,2014,22(5):936–943.(WANG Hao,LIN Yifu,WU Dongliang,et al.Fuzzy hierarchy analysis for treatment effect of complex cutting high slope disease[J].Journal of Engineering Geology,2014,22(5):936–943.(in Chinese))
[13]王恭先,徐峻岭,刘光代,等.滑坡学与滑坡防治技术[M].北京:中国铁道科学出版社,2004:135–139.(WANG Gongxian,XU Junlin,LIU Guangdai,et al.The science and control technology of landslide[M].Beijin:China Railway Science Press,2004:135–139.(in Chinese))
[14]WANG H,LIAO X P.Mechanical characters of relaxing zone of slopes due to excavation[C]//CHEN Z Y,ZHANG J M,LI Z K,et al ed.Proceedings of the 10th International Symposium on Landslides and Engineered Slopes.London:Taylor&Francis Group,2008:501–506.
[15]HOEK E,CARRANZA-TORRES C,CORKUM B.Hoek-Brown failure criterion–2002 edition[C]//HAMMAH R,BAWDEN W F,CURRAN J,et al ed.Proceedings of the North American Rock Mechanics Society NARMS-TAC 2002.Toronto:University of Toronto Press,2002:267–273.
[16]王浩,廖小平.边坡开挖卸荷松弛区的力学性质研究[J].中国地质灾害与防治学报,2007,18(增1):5–10.(WANG Hao,LIAO Xiaoping.Research on the mechanical character of relaxing zone of slopes due to excavation[J].The Chinese Journal of Geological Hazard and Control,2007,18(Supp.1):5–10.(in Chinese))
[17]王浩.福建省永春至永定高速公路龙岩段K227滑坡设计咨询报告[R].福州:福州大学岩土与地下工程研究中心,2010.(WANG Hao.The consulting report for K227 landslide which is in Yongchun to Yongding Expressway Longyan section in Fujian Province design[R].Fuzhou:Geotechnical and Underground Engineering Research Center,Fuzhou University,2010.(in Chinese))