降雨条件下微型桩—土共同作用机理研究

发布时间：2018-07-20 13:07

【摘要】：边坡稳定性是岩土工程和土木工程领域的一个重要研究课题。微型桩边坡支护是一种新的边坡支护方式。与传统的抗滑维稳支撑结构相比,微型桩具有施工快捷方便,体积小,施工快速,适用范围广等优点。微型桩作为控制滑坡稳定性的新技术,其在工程中的实际应用相对较晚,且对项目的实际使用多为经验法,相关设计理论等也还不完善。关于微型桩加固的目前研究正处于初步阶段,特别是对于雨后的微型桩边坡修复工程,这对微型桩未来的发展和应用是非常不利的。基于室内模型试验,研究了降雨条件下微型桩支护边坡作用下微型桩内部应力分布,桩侧土压力分布和桩顶位移情况。试验结果表明:试验前,采用分层填筑的方法由坡底向坡顶制作边坡,由于制作顺序是从下而上进行,因此存在下层坡体被过多击实的问题。从而导致边坡上层土体相较于下层而言较松,加载后变形大。微型桩的受力特点大致相同,但同一根桩上、中、下部位受力特点有明显差别。表现为中部应变最大,下部应变其次,上部应变最小,且桩体上部应变值为负,由此可以推断桩体由下到上弯矩方向相反,中部是反弯点;基于ABAQUS有限元软件针对室内模型试验建立降雨入渗条件下微型桩支护边坡的有限元模型,并对其雨后边坡稳定性进行了相应的分析,分析了降雨持续时间和桩间距对边坡稳定性的影响。并得出了一系列结论:随着降水量的增加,边坡土体的饱和度增加;由于微型桩的阻塞作用,微型桩位置处土体左右饱和度始终呈现出阶梯型变化,与无桩边坡区别明显;边坡的应力也随着降雨而变化,并且桩侧位置出现应力集中现象,表明随着潜在滑动面的发展,微型桩在逐渐发挥阻碍作用。比较模型试验和有限元模拟表明,微型桩结构对于滑坡的加固效果明显,与传统的抗滑桩结构相比,微型桩属于柔性支护,其虽然不能像传统的支护桩一样单独发挥加固作用,但其可通过微型桩群桩之间相互作用而改善其自身刚度不足等缺陷,因此,微型桩多被认为是一种支护系统,通过桩与桩之前的相互作用而产生支护的效果,其为进一步研究微型桩提供了理论基础。
[Abstract]:Slope stability is an important research topic in geotechnical and civil engineering fields. Micro pile slope support is a new way of slope support. Compared with the traditional anti-slide support structure, micro-pile has the advantages of quick and convenient construction, small volume, fast construction and wide range of application. As a new technique to control landslide stability, micro-pile is relatively late in practical application in engineering, and the practical use of the project is mostly empirical method, and the related design theory is not perfect. The research on micro-pile reinforcement is at the initial stage, especially for the slope restoration of micro-pile after rain, which is very disadvantageous to the development and application of micro-pile in the future. Based on indoor model tests, the internal stress distribution, soil pressure distribution and pile top displacement of micro-pile supporting slope under rainfall were studied. The test results show that before the test, the method of stratified filling is used to make slope from the bottom to the top of the slope. Because the production sequence is from the bottom to the top, there is the problem of the lower slope body being overcompacted. As a result, the upper soil mass of the slope is looser than that of the lower layer, and the deformation is large after loading. The stress characteristics of micro pile are roughly the same, but there are obvious differences between the upper, middle and lower parts of the same pile. The maximum strain is in the middle, the strain in the lower part is the second, the strain in the upper part is the smallest, and the strain value of the upper part of the pile is negative. It can be concluded that the direction of the pile bending moment is opposite from the bottom to the top, and the middle part is the reverse bending point. Based on Abaqus finite element software, the finite element model of micro-pile supporting slope under rainfall infiltration condition is established for indoor model test, and the stability of slope after rain is analyzed accordingly. The influence of rainfall duration and pile spacing on slope stability is analyzed. A series of conclusions are drawn as follows: with the increase of precipitation, the saturation of slope soil increases, because of the blocking effect of micro-pile, the saturation of left and right soil in the position of micro-pile always presents ladder type change, which is obviously different from that of non-pile-free slope. The stress of the slope also changes with rainfall and the stress concentration on the side of the pile shows that with the development of the potential sliding surface the micro-pile is gradually playing a role of hindrance. Compared with the traditional anti-slide pile structure, the micro-pile belongs to flexible support, although it can not play a strengthening role alone as the traditional supporting pile, compared with the traditional anti-slide pile structure, the micro-pile structure has obvious effect to the landslide reinforcement, compared with the traditional anti-slide pile structure, the micro-pile structure belongs to flexible support. However, it can improve the deficiency of its own stiffness by interaction between pile groups. Therefore, micro-pile is considered to be a kind of supporting system, and the effect of supporting is produced by interaction between pile and pile before. It provides a theoretical basis for the further study of micro pile.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

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