【作者】 孙磊；

【导师】 李哲；

【作者基本信息】 长安大学 ， 建筑与土木工程（专业学位）， 2020， 硕士

【摘要】 本文紧密结合黄土高填方边坡稳定性分析问题,依托于延安市南泥湾机场南端高填方边坡工程,基于抗剪强度理论,采用现场监测手段、室内试验研究和理论研究相结合的方法,对分层压实度变化及各向异性的高填方边坡稳定性分析方法进行了研究,分析了黄土高填方边坡的运动规律,建立了速率识别区间和不同深度考虑各向异性的位移识别区间,提出了将熵权法和证据推理相结合对黄土高填方边坡安全评估的方法,主要研究工作及成果如下。(1)对高填方坡体多级台阶均匀埋设深部水平位移、分层沉降及表面位移监测点,建立了可追踪高填坡体表面至深部运动的位移监测系统,通过分析不同空间位置点随时间的运动规律,划分出不同运动效果的区域-前坡区和后坡区,得出后坡区域的坡体位移大于前坡区域,且最大位移主要出现在左右坡肩的位置坡中次之,而前坡区域的最大位移则出现在坡中的位置两侧坡肩次之。(2)通过自研剪切仪器对不同压实度黄土试样正交方向抗剪强度进行研究,得出了峰值抗剪强度与压实度的线性拟合方程以及其对应的剪切位移与法向应力的线性拟合方程,给出了多层非均质压实度在垂直分层界面方向的抗剪强度与单一压实度的关系。通过对不同压实度试样进行单轴压缩试验获得了压实度与埋深的分段拟合关系式,最终通过联立求解划分出了考虑分层压实度变化的正交剪切方向位移识别区间。(3)将熵权法和证据理论相结合,提出了一种客观赋权并可以将各向异性以及分层压实度变化考虑到黄土高填方边坡稳定性分析中的方法,基于试验构造的正交方向识别区间进行分析,分别给出了边坡状态概率分布的下限和上限。采用各区间界限值对该评估方法进行了检验,结果表明这种方法能够准确识别边坡所处状态并及时发出预警,在机场运营期限内可以有效保障人民生命安全。更多还原

【Abstract】 This paper closely integrates the stability analysis of loess high-fill slope.Taking the high-fill slope at the southern end of the Nanniwan Airport in Yan’an as a background,this paper uses a combination of on-site monitoring,indoor tests,and theoretical analysis to study the high-fill slope stability analysis method considering the increase in compaction with depth and strength anisotropy.Firstly,the movement law of loess high fill slope is analyzed.Secondly,the rate recognition interval and the displacement recognition interval considering the anisotropy at different depths are established.Finally,the method of combining entropy weight method and evidence reasoning to evaluate the safety of loess high fill slope is proposed.The main research work and results are as follows:(1)The multi-level steps of the high-fill slope body are evenly buried with deep horizontal displacement,layered settlement and surface displacement monitoring points.By analyzing the movement laws of different spatial location points over time,the regions with different movement laws are divided,namely the front slope area and the back slope area.It is concluded that the slope displacement in the back slope area is greater than that in the front slope area.The maximum displacement in the back slope area mainly occurs at the position of the left and right slope shoulders,but the maximum displacement in the front slope area occurs at the middle position of the slope.(2)The self-developed shearing instrument was used to study the shear strength of loess samples with different compactness in orthogonal shearing direction.The linear fitting equation of peak shear strength with compaction degree and the linear fitting equation of corresponding shear displacement with normal stress are obtained.In addition,the relationship between the shear strength of the multi-layer heterogeneous compaction in the direction of the vertical layered interface and the homogeneous compaction is given.By performing uniaxial compression test on samples with different degrees of compaction,the piecewise fitting relationship between the degree of compaction and the buried depth is obtained.Finally,through the simultaneous solution,the identification interval of the orthogonal shear direction displacement considering the increase of compaction degree with depth is divided.(3)Using the combination of entropy weight method and evidence theory,an objective weighting method for safety evaluation of loess high fill slope is proposed,which takes into account the impact of strength anisotropy and compaction increasing with depth on slope stability.Based on the analysis of the orthogonal direction recognition interval from the test results,the lower limit and upper limit of the slope state probability distribution are given respectively.The evaluation method was tested with the boundary value of each interval.The results show that this method can accurately identify the state of the slope and send out early warning in time,so that the safety of people’s lives can be effectively guaranteed during the operation period of the airport.更多还原