基于FLAC的极限状态黄土高边坡强度参数反演
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摘要
评价边坡稳定性关键问题是确定滑动面和可靠的抗剪强度参数。基于数值模拟技术,提出一种新的方法,可在无需事先假定滑动面的情况下得到可靠的强度参数。通过对兰州地区30个极限状态黄土边坡的坡高和坡宽参数进行统计,发现二者呈线性关系,且拟合度较高。根据所得到的回归方程,采用FLAC建立边坡模型,利用强度折减法对兰州地区边坡进行强度参数反演,将4个邻近高度边坡得到的参数反演曲线绘于同一坐标系中,得到该坡段综合强度参数值。反演结果表明:随着坡高的增加,黄土内摩擦角逐渐减小,黏聚力增大。根据计算结果,绘制60~120 m边坡高度下强度参数综合反演曲线,可直接进行黄土高边坡稳定性评价,提高了工作效率,也为高边坡几何形态的设计提供可靠的数据支持。
Determining sliding surface and reliable shear strength parameters are crucial issues in evaluating slope stability. A new method based on numerical simulation technology is proposed to obtain reliable strength parameters without presuming the sliding surface. The relationship between heights and widths of thirty loess slopes at limit state in Lanzhou region were found to be linear,and the fitting degree was high. According to the obtained regression equation,FLAC was applied to establish the slope model,and strength reduction method was used to inverse the strength parameters of slope at limit state. Furthermore,the parameter inversion curves of four adjacent high slopes were drawn in the unified coordinate system,and the comprehensive strength parameters of the segment were acquired. The inversion results show that with the increase of slope height,the cohesive force of loess increases gradually but internal friction angle decreases. According to the calculation results,the comprehensive inversion curves of strength parameters of slope with heights from 60 m to 120 m are drawn. The method could directly evaluate the stability of high loess slope,improve the working efficiency,and also provides reliable data to support the geometry design of high loess slope.
Determining sliding surface and reliable shear strength parameters are crucial issues in evaluating slope stability. A new method based on numerical simulation technology is proposed to obtain reliable strength parameters without presuming the sliding surface. The relationship between heights and widths of thirty loess slopes at limit state in Lanzhou region were found to be linear,and the fitting degree was high. According to the obtained regression equation,FLAC was applied to establish the slope model,and strength reduction method was used to inverse the strength parameters of slope at limit state. Furthermore,the parameter inversion curves of four adjacent high slopes were drawn in the unified coordinate system,and the comprehensive strength parameters of the segment were acquired. The inversion results show that with the increase of slope height,the cohesive force of loess increases gradually but internal friction angle decreases. According to the calculation results,the comprehensive inversion curves of strength parameters of slope with heights from 60 m to 120 m are drawn. The method could directly evaluate the stability of high loess slope,improve the working efficiency,and also provides reliable data to support the geometry design of high loess slope.
引文
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[2]李萍,王秉纲,李同录.自然类比法在黄土路堑边坡设计中的应用研究[J].公路交通科技,2009,26(2):1-5.
[3]赵尚毅,郑颖人,张玉芳.极限分析有限元法讲座——Ⅱ:有限元强度折减法中边坡失稳的判据探讨[J].岩土力学,2005,26(2):332-336.
[4]陈力华,靳晓光.有限元强度折减法中边坡三种失效判据的适用性研究[J].土木工程学报,2012,45(9):136-146.
[5]房智恒,王李管,彭南良,等.高陡边坡整体与局部失稳的强度折减及安全度判别分析[J].重庆大学学报(自然科学版),2015,38(6):8-14.
[6]刘超.黄土高边坡抗剪强度参数反演研究[D].西安:长安大学,2014.
[7]刘文红,张亚卿,李同录,等.根据参数反演结果分析非饱和黄土边坡破坏机理[J].工程地质学报,2014,22(5):915-920.
[8]徐汉斌,王军.反算法中滑坡稳定系数的取值问题[J].四川地质学报,1999,19(1):86-89.
[9]李萍,黄丽娟,李振江,等.甘肃黄土高边坡可靠度研究[J].岩土力学,2013,34(3):811-817.
[10]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):3381-3388.
[11]GRIFFTHS D V,LANE P A.Slope Stability Analysis by Finite Elements[J].Geotechnique,1999,49(3):387-403.
[12]彭文斌.FLAC3D实用教程[M].北京:机械工业出版社,2007.
[13]郑志勇,余海兵,徐海清.软硬岩互层边坡的破坏模式及稳定性研究[J].长江科学院院报,2016,33(9):102-106.
[14]王科,王常明,王彬,等.基于Morgenstern-Price法和强度折减法的边坡稳定性对比分析[J].吉林大学学报(地球科学版),2013,43(3):902-907.
[15]郑明新.论滑带土强度特征及强度参数的反算法[J].岩土力学,2003,24(4):528-532.
[16]李同录,刘超,李萍.甘肃天水地区黄土极限状态边坡的统计分析[J].地球科学与环境学报,2013,35(2):107-112.
[17]雷晓峰.黄土边坡强度参数的选取及应用[D].西安:长安大学,2005.
[18]张少宏.黄土边坡稳定计算中参数的敏感性分析[J].水利与建筑工程学报,2003,1(3):40-42.
[19]赵永虎,刘高,毛举,等.基于灰色关联度的黄土边坡稳定性因素敏感性分析[J].长江科学院院报,2015,32(7):94-98.