西南某红层机场试验段高填方边坡稳定性研究

发布时间：2018-05-30 01:27

本文选题：加筋土 + 稳定性　；参考：《成都理工大学》2015年硕士论文

【摘要】：在西南红层地带等地形复杂地区开展基础设施建设通常相当困难,具有可用地资源极为紧缺与缺少适合大规模工程建设的自然“开阔平地”的突出矛盾,这意味着在这类山地中进行开山填沟造地的人工高填方工程将成为解决建设用地的重要途径之一,高填方体的稳定性便成了影响工程安全稳定运营的关键。本文以某机场南边界加筋土边坡为研究对象,通过对国内外加筋土边坡的研究现状及目前仍存在的问题等方面进行归纳总结,结合现场勘察、室内分析,掌握了研究区的地质背景及加筋土边坡失稳的影响因素,揭示了其变形破坏机制。在进行地质分析基础上,采用数值分析的方法,对影响加筋土边坡稳定性的因素进行分析,研究了降雨入渗条件下边坡渗流场特征及稳定性变化特征,然后以极限平衡法计算为研究手段,通过改变影响其稳定性的放坡坡比,对稳定性系数的变化进行优化分析,得到既保证安全又兼顾经济的加固方案。主要研究成果如下:(1)加筋边坡的破坏发展过程可以归纳为:由于降雨导致边坡重度增大,填土抗剪强度降低,在坡内形成贯通的圆弧形滑面,滑动面绕过加筋土挡土墙的加筋带,从软化的坡脚剪出。初步判断加筋土边坡失稳模式为基底软弱层的剪切滑移破坏,而降雨入渗是边坡失稳的诱发因素。结合边坡变形破坏特征及稳定性影响因素的研究,该边坡发生了整体滑移破坏。(2)经过反压等加固措施处理的边坡,结合变形迹象发展趋势及位移监测分析,判断现阶段边坡处于缓慢蠕滑阶段。导致边坡经过前期治理但仍然发生变形的主要诱因是强降雨。(3)随着降雨持时的增加,雨水渗入到边坡内部,导致加筋土坡内地下水位线的抬高,地下水位线的上升引起渗流场的变化,渗流场特征又决定着坡体内基质吸力的分布,基质吸力的变化将会导致非饱和土抗剪强度的变化,从而影响着坡体的整体稳定性。(4)随着降雨持续时间延续,出现边坡稳定性系数缓慢下降到最小值,降雨停止后开始逐渐回升的现象。(5)天然工况坡比为1:0.25条件下,边坡处于基本稳定状态,但安全储备较低。从安全和经济角度考虑,坡比1:0.5较为合适。鉴于工程的复杂性,暴雨工况下需加强边坡排水,尤其是坡体内部积水应当及时排走,从而保障边坡的稳定。
[Abstract]:It is usually very difficult to carry out infrastructure construction in areas with complex topography such as the southwest red beds, and there is a prominent contradiction between the extremely short supply of available land resources and the lack of natural "open flat land" suitable for large-scale engineering construction. This means that the artificial high fill project in this kind of mountainous area will become one of the important ways to solve the problem of construction land, and the stability of the high fill body will become the key to the safe and stable operation of the project. In this paper, the reinforced soil slope at the south boundary of an airport is taken as the research object. Through the summary of the current research situation and the existing problems of the reinforced soil slope at home and abroad, combined with the field investigation, the indoor analysis is carried out. The geological background of the study area and the influencing factors of the instability of reinforced soil slope are grasped, and the mechanism of deformation and failure is revealed. On the basis of geological analysis, the factors influencing the stability of reinforced soil slope are analyzed by numerical analysis method, and the characteristics of seepage field and stability of slope under rainfall infiltration are studied. Then, the limit equilibrium method is used as the research method. By changing the slope ratio which affects the stability of the slope, the stability coefficient is optimized and analyzed, and a reinforcement scheme is obtained, which can guarantee the safety as well as give consideration to the economy. The main research results are as follows: (1) the process of failure and development of reinforced slope can be summarized as follows: due to heavy increase of slope caused by rainfall, shear strength of fill soil decreases, and a circular arc slip surface is formed in the slope. The sliding surface bypasses the stiffened belt of the reinforced earth retaining wall and is cut out from the softened foot of the slope. It is preliminarily judged that the failure mode of reinforced soil slope is shear slip failure of the weak layer of the base, and rainfall infiltration is the inducing factor of slope instability. Combined with the study of the deformation and failure characteristics of the slope and the influencing factors of the stability of the slope, the slope with integral slippage failure occurred in the slope, which has been treated with backpressure and other reinforcement measures, combined with the development trend of the deformation signs and the monitoring and analysis of the displacement. It is judged that the slope is slowly creeping at the present stage. With the increase of rainfall duration, Rain Water seeps into the slope, which leads to the elevation of underground water level in reinforced soil slope. The rise of underground water level leads to the change of seepage field, and the characteristics of seepage field determine the distribution of matrix suction in slope, and the change of matrix suction will lead to the change of shear strength of unsaturated soil. Thus affecting the overall stability of the slope. 4) with the duration of the rainfall, the slope stability coefficient slowly decreased to the minimum value, and the slope ratio began to rise gradually after the rainfall stopped. The slope ratio of natural conditions was 1: 0.25. The slope is basically stable, but the safety reserve is low. From a security and economic point of view, the slope ratio of 1: 0.5 is more appropriate. In view of the complexity of the project, it is necessary to strengthen the drainage of the slope under heavy rain conditions, especially the water in the body of the slope should be discharged in time to ensure the stability of the slope.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43

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