【作者】 张鹏；

【导师】 杨兵；

【作者基本信息】 西南交通大学 ， 建筑与土木工程（专业学位）， 2018， 硕士

【摘要】 边坡的稳定性在岩土工程界一直是一个热门的话题,目前来说,稳定性分析领域均质边坡已经研究较多了。我国幅员辽阔,山地众多,自然界中不可避免的存在许多非均质地质体,含软弱夹层边坡作为其中具有代表性的一种,其稳定性受到广泛关注。边坡的抗剪强度往往在夹层处表现为不连续,又因边坡的失稳破坏常常发生在夹层处,因此边坡中软弱夹层往往成为边坡失稳的决定性因素。滑坡常常是由地震触发的。我国地处两大活跃的地震带之间,地震发生的频率较高,西部山区又与两大地震带区域相重叠,地震的发生会使原本脆弱的地质条件变得更加恶劣。大量的地震灾害表明,滑坡的发生与近断层地震动密切关联,近断层区域滑坡发生的概率远大于远震区。本文借助有限差分程序FLAC3D,建立概化边坡模型,采用多种边坡失稳的判别依据,对均质土质边坡、岩质边坡、含软弱夹层边坡静力安全系数,脉冲速度波作用下动力安全系数进行了探讨,并对不同工况下含软弱夹层边坡在脉冲地震动作用下边坡动力响应规律、破坏模式进行了初步的探讨。主要研究了软弱夹层的几何形态及边坡的几何形态对边坡安全系数、动力响应规律、破坏模式的影响。主要的工作及研究结果如下:(1)均质土质边坡在4种边坡失稳判别依据下得出的安全系数具有一致性,岩质边坡的安全系数在4种边坡失稳判别下得出的安全系数值相近。FLAC3D在计算均质边坡安全系数时的结果与极限平衡法的结果相近。(2)边坡中存在软弱夹层会降低边坡的静力安全系数;软弱夹层在边坡的位置对边坡静力安全系数影响较大,表现为夹层在边坡中的位置越低,边坡静力安全系数越小;夹层位置低于四分之三坡高时夹层位置变化对边坡静力安全系数影响较大,夹层位置低于四分之三坡高时,夹层的位置升高,会显著提高边坡的安全系数;夹层位置高于四分之三坡高时,边坡静力安全系数随夹层位置的升高增加缓慢,其安全系数更接近均质边坡。用传统极限平衡法计算含软弱夹层边坡的静力安全系数时结果失真。(3)采用有限差分程序FLAC3D对一个振动台单面边坡实验进行模拟,通过对比数值模拟和实验所得加速度放大系数,发现采用FLAC3D模拟单面坡效果较好。(4)对含软弱夹层边坡的动力安全系数求解,发现软弱夹层在边坡中的位置、倾角、边坡的坡高和坡角变化会影响边坡的动力安全系数,表现为夹层的位置越低,含软弱夹层边坡承受地震作用的能力越弱,边坡的动力安全系数越小;坡高越高,坡角越大,边坡的动力安全系数也越小。边坡的破坏模式受夹层的影响非常显著,表现为夹层低于二分之一坡高时,边坡发生破坏时破坏体会从夹层与坡面交界处剪出,夹层位置高于二分之一坡高后,边坡破坏时的剪出口位于坡脚处。夹层的位置越低,坡顶发生拉伸破坏的深度越深,边坡的坡高越高,坡角越大,坡顶发生拉伸破坏的深度也越深。(5)为了探讨含软弱夹层边坡的动力响应,对边坡材料参数不折减的情况下输入3种地震波,通过提取坡面和坡内关键点的加速度曲线,求解相应的加速度放大系数;对比夹层在不同边坡位置处的加速度放大系数,发现加速度放大系数沿高程总体是放大的;夹层位置的升高会影响加速度放大系数,夹层位置越高,加速度放大系数越小,边坡的动力特性就越接近均质边坡。当夹层位置低于二分之一坡高时,双脉冲地震波的加速度放大系数大于单脉冲地震波,当夹层位置高于二分之一坡高时,表现为单脉冲地震波作用下加速度放大系数比双脉冲地震波的加速度放大系数大。坡高和坡角的变化显著影响边坡的加速度放大系数规律,表现为坡高坡角越大,加速度放大系数越大;软弱夹层倾角也会影响边坡的加速度放大系数,含反倾软弱夹层的加速度放大系数大于含水平软弱夹层大于含顺倾软弱夹层。更多还原

【Abstract】 The stability analysis of slope is always a hot topic in geotechnical engineering field.In the current study of slope stability,homogeneous slope is the object of much research.China is a vast country with many mountains.There are inevitably many heterogeneous mountains in nature.Slope with weak interlayer,as one of representative;its stability has been widely concerned.As the discontinuous surface of strength in slope,the failure of slope instability often starts from interlayer,so the weak interlayer in slope becomes the controlling factor of slope instability.Earthquakes play an important role in the occurrence of landslides.China is located between two active seismic zone,higher frequency of the earthquake,the western mountains overlape with two seismic area,the earthquake can transform a fragile geological conditions become more severe.A large number of seismic disasters show that the occurrence of landslide is closely related to the near fault ground vibration,and the probability of the near fault area landslide is much higher than that of the far earthquake area.The finite difference program FLAC3 D is used in this paper to analyze the slope model.The static safety factor of homogeneous soil slope,rock slope,soft interbedded slope and dynamic safety factor under pulse velocity wave are discussed by using various criteria to distinguish slope instability and the dynamic response and failure modes of soft interbedded slope under pulse ground vibration are discussed.The main work and research results are as follows:(1)Homogeneous soil slopes under four kinds of standards of the slope unstability of consistent safety coefficient,the safety factor of rock slope under the instability of 4 kinds of standards of safety factor though not consistency,but the difference is smaller.The results of FLAC3 D in calculating the slope safety factor of homogeneous slope are similar to those of the limit equilibrium method.(2)The existence of weak interlayer in slope will reduce the static safety factor of slope;The position of the weak interlayer on the slope has a great influence on the static safety coefficient of the slope,which shows that the lower the position of the interlayer in the slope,the smaller the static safety coefficient of the slope;Weak interlayer position less than half the high slope,soft interlayer position changes greatly influenced by the static safety factor of slope,soft interlayer position less than half the high slope,the location of the soft interlayer,will significantly improve the safety factor of slope;When the position of weak interlayer is more than one half,the slope static safety coefficient increases slowly with the increase of weak interlayer position,and the safety coefficient gradually approaches the homogeneous slope.The traditional limit equilibrium method is used to calculate the static safety coefficient of slope with weak interlayer.(3)Using the finite differential program FLAC3 D to simulate a single side slope of a vibrating table.By comparing the numerical simulation with the experimental acceleration amplification coefficient,it is found that the FLAC3 D simulation of single slope has a good effect,which has similar laws in the simulation of double slope.(4)It is found that the position and inclination Angle of the weak layer,slope height and slope Angle of soft interbedded slope will affect the dynamic safety coefficient of slope;The lower the location of the weak layer,the lower ability of the slope with weak layer can bear an earthquake and the the dynamic safety factor of slope will be lower.The dynamic safety factor of slope decreases with the increase of slope height and slope Angle.The failure mode of slope is obviously affected by interlayer.When the position of weak interlayer is less than half of slope height,slope failure occurs at interlayer.When the position of weak interlayer is higher than half of slope height,the shear outlet of slope failure is located at the foot of slope.The lower the position of the weak interlayer,the deeper the tensile failure will occur at the top of the slope.The higher the slope height,the greater the slope Angle,the deeper the tensile failure will develop at the top of the slope.(5)In order to research the dynamic response of slope with weak interlayer,the material parameters of slope under the condition of no reduction will bear three seismic wave input,by extracting key acceleration curve slope and slope,solving the corresponding acceleration amplification factor.By comparing the acceleration amplification coefficient of the interlayer at different slope positions,it is found that the acceleration amplification coefficient is generally enlarged along the height.The change of inclination Angle of weak interlayer has little influence on the acceleration amplification coefficient.The increase of the position of the weak interlayer will affect the acceleration amplification coefficient.The higher the position of the weak interlayer,the smaller the acceleration amplification coefficient,the closer the dynamic characteristics of the slope will be to the homogeneous slope.When the weak interlayer position is less than half the high slope,the double pulse seismic acceleration amplification factor is greater than the single pulse wave,when the weak interlayer position higher than half the high slope,single pulse under the action of seismic acceleration amplification factor is bigger than double pulse acceleration amplification coefficient of seismic wave.The change of slope height and slope angle significantly affects the law of slope acceleration amplification coefficient,the higher the slope angle,the greater the acceleration amplification factor.As the height and angle of slope increases,the acceleration amplification factor of slope will also insrease.The Angle of the weak layer affects the acceleration of the slope,the acceleration amplification coefficient of the slope with reverse weak interlayer is largest.更多还原