大轴重和长时重力荷载对路堤边坡稳定性影响及设计优化

发布时间：2018-04-12 23:05

  本文选题：大轴重 + 边坡稳定性　； 参考：《西南交通大学》2017年硕士论文

【摘要】：边坡稳定性是路堤边坡设计优化的重要依据。在重载铁路运输提高列车轴重发展趋势的背景下,开展大轴重重载铁路路堤边坡设计优化工作,以细粒土、碎石土、硬块石土三种常见路堤填料分别填筑的路堤为研究对象,针对路堤正常服役及浸水软化两种工况,采用瑞典条分法分析45t轴重及以下列车荷载对边坡稳定性影响规律,从路堤高度、边坡坡度、路肩宽度三个角度对大轴重重载铁路路堤边坡进行设计优化。此外,为保证高速铁路长期安全稳定运营,须控制边坡在长时重力荷载作用下具有时间效应的变形,在土体变形时间效应试验成果基础上,提出边坡土体变形时间效应分析方法,利用ABAQUS有限元软件建立分析模型,基于不同等级线路的长期变形状态控制目标,针对斜坡地基下高速铁路路堤长期稳定性问题进行分析,并提出设计优化方法。主要结论如下:(1)路堤边坡安全系数对列车荷载敏感性受填料种类影响显著,其原因为,首先,随路堤填料强度的提高,滑床能为滑体提供更大抗滑力,由列车荷载引起的下滑力对安全系数影响程度减弱;其次,路堤标准断面高度随填料强度提高而增加,与列车荷载相比,路堤自重对边坡稳定性影响权重升高;再者,当路堤填料内摩擦角较高时,路堤内滑动面位于应力较低的坡面附近,列车荷载同滑体上部相交区域较小,导致边坡稳定性受轴重影响程度较低。(2)在大轴重列车荷载下,需保证路堤填料浸水软化时边坡稳定安全系数Fs≥1,在正常服役时Fs≥1.25,据此计算路堤临界高度、临界坡比、临界路肩宽度随轴重变化规律。临界高度同轴重接近线性的负相关关系,其规律受路堤填料种类影响不显著。临界坡比与临界路肩宽度同轴重接近线性的正相关关系,且两因素对轴重敏感性因填料而异,随填料强度升高,轴重对临界坡比及临界路肩宽度影响程度降低。在25～45t轴重列车荷载作用下,分别以细粒土、碎石土、硬块石土作为路堤填料时,路堤高度阈值变化范围分别是8～5m、12～9m、20～17m,边坡坡比阈值为1:1.5～1:2、1:1.5～1:1.75、1:1.5～1:1.75,路肩宽度阈值为 1～3.5m、1～2m、1～2m。(3)提出了通过整体剪应力比代表土体变形时间效应的分析方法,并针对山区多斜坡地基条件,利用该方法对不同地基坡度下边坡土体变形时间效应进行了分析,根据有砟轨道边坡达到缓慢稳定状态、无砟轨道边坡达到快速稳定状态两个原则指导路堤设计,对路堤填料以及工程措施提出了相应的要求:对于无砟轨道,在地基坡度低于或等于1:5时,压实的A、B组填料即可达到控制目标;在地基坡率陡于1:5时,需在压实的A、B组填料基础上控制路堤高度;在地基坡率达到1:2.5时,除使用压实的A、B组填料外还需采取增稳措施。对于有砟轨道,当地基坡率达到1:2.5时,需进行整体检算或采取增稳措施。
[Abstract]:Slope stability is an important basis for optimization of embankment slope design.Under the background of increasing the development trend of train axle load in heavy-haul railway transportation, the design optimization work of embankment slope of large-axle heavy load railway embankment is carried out. The embankment filled with three kinds of common embankment fillers, such as fine grained soil, crushed stone soil and hard block stone soil, is taken as the research object.In view of the two working conditions of embankment in normal service and soaking and softening, the Swedish strip method is used to analyze the influence of 45 t axle load and the following train load on slope stability, from the height of embankment and slope gradient,Three angles of shoulder width are used to optimize the design of heavy load railway embankment slope.In addition, in order to ensure the long-term safe and stable operation of high-speed railway, it is necessary to control the deformation of slope with time effect under the action of long-term gravity load, and based on the experimental results of soil deformation time effect,The time effect analysis method of slope soil deformation is put forward, and the analysis model is established by using ABAQUS finite element software. Based on the control target of long-term deformation state of different grade lines, the long-term stability of high speed railway embankment under slope foundation is analyzed.The design optimization method is also proposed.The main conclusions are as follows: (1) the safety factor of embankment slope has a significant effect on the train load sensitivity due to the fact that, first of all, with the increase of the strength of embankment filler, the sliding bed can provide more anti-slide force for the slide body.Secondly, the height of standard section of embankment increases with the increase of filling strength, compared with the train load, the weight of embankment deadweight on slope stability is increased.When the internal friction angle of embankment filler is high, the slip surface of embankment lies near the slope with lower stress, and the intersection area between the train load and the upper part of the sliding body is smaller, which results in the slope stability being affected less by axle load.It is necessary to ensure the slope stability safety factor Fs 鈮，

本文编号：1741817