盘径对水平力作用下扩盘桩土体破坏状态影响研究

发布时间：2018-06-04 05:12

本文选题：混凝土扩盘桩 + 盘径　；参考：《吉林建筑大学》2017年硕士论文

【摘要】：目前,关于混凝土扩盘桩水平承载力的理论和试验研究已取得了一定的成果,但仍处于初步阶段。分析目前的研究现状,对混凝土扩盘桩在水平力作用下的研究还存在一些问题:首先,混凝土扩盘桩与直孔桩相比,桩周土受力情况发生较大变化,因此,目前参考普通直孔桩得出的混凝土扩盘桩单桩极限抗倾覆承载力的计算方式不够合理。其次,已有的研究中,多数是对桩体本身的破坏研究,而对桩周土体的破坏对承载力的影响的研究几乎没有。第三,对于单桩承载力的主要影响因素如:承力盘直径、间距、位置、坡度、数量等,只是做了定性的分析,缺少可靠的理论依据。所以,还需对各影响因素、土体破坏状态作进一步研究,提出更为合理的混凝土扩盘桩水平承载力计算模式。本文选定承力盘盘径这一影响因素,通过理论分析和小比例模型试验的方法深入探讨盘径对混凝土扩盘桩水平承载力及桩周土体破坏状态的影响。理论分析采用ANSYS有限元模拟软件,建立不同盘径的扩盘桩桩土模型,对扩盘桩和土体的位移和应力结果进行对比分析。小比例模型试验则在理论分析的基础上,将桩土模型尺寸按1:30缩小,确定试验桩土模型。试验过程中随时记录荷载、位移数据,并用相机记录桩土相互作用情况。最后,对比分析理论与试验结果,清晰的看出水平力作用下桩土相互作用机理,得出盘径与桩径的最优比例,并首次提出考虑土体破坏的前提下,混凝土扩盘桩水平极限承载力计算模式。本文的重点及创新之处在于试验方法,试验方法依然采用原状土可视试验装置。由于一般建(构)筑物通常处于竖向力和水平力共同作用的环境中,所以本次试验加载装置在原有竖向力加载装置的基础上经过反复推敲、试验、改进,实现了竖向力和水平力同时加载。同时在已有试验的基础上,对取土器及取土方法进一步改进,力求获取更加完整的原状土试块。由于试验过程全程可视,通过对桩周土体破坏过程的观察记录,弥补了扩盘桩研究中对土体破坏状态研究的空白。本文关于盘径对混凝土扩盘桩水平承载力及土体破坏状态的影响研究成果,将完善扩盘桩桩型设计理论,丰富扩盘桩水平承载力计算方法,为混凝土扩盘桩在承受水平力的建(构)筑物中的应用起到了极大的推动作用。同时,对试验方法的改进与创新,为桩基础的研究发展提供了借鉴。
[Abstract]:At present, some achievements have been made in the theoretical and experimental study of the horizontal bearing capacity of concrete pile, but it is still in the initial stage. Based on the analysis of the present research situation, there are still some problems in the study of concrete pile under horizontal force. Firstly, compared with the pile with straight hole, the stress on the soil around the pile is greatly changed. At present, the calculation method of ultimate capsizing bearing capacity of single pile with concrete expansion plate pile is not reasonable. Secondly, most of the existing researches focus on the failure of the pile itself, but there is little research on the influence of the soil failure around the pile on the bearing capacity. Thirdly, the main influencing factors of bearing capacity of single pile such as diameter, spacing, position, slope and quantity of bearing plate are only qualitatively analyzed, lacking reliable theoretical basis. Therefore, it is necessary to further study the influence factors and the failure state of soil, and put forward a more reasonable calculation model of horizontal bearing capacity of concrete expanded disc pile. In this paper, the influence factors of bearing disc diameter are selected, and the influence of disc diameter on horizontal bearing capacity and failure state of soil around pile is discussed by theoretical analysis and small scale model test. The ANSYS finite element simulation software was used to establish the pile-soil model with different plate diameters, and the results of displacement and stress of the expanded pile and soil were compared and analyzed. On the basis of theoretical analysis, the pile-soil model size is reduced at 1:30 to determine the pile-soil model. The load and displacement data were recorded at any time during the test, and the pile-soil interaction was recorded by camera. Finally, by comparing the theoretical and experimental results, the mechanism of pile-soil interaction under horizontal force is clearly seen, and the optimal ratio of disc diameter to pile diameter is obtained, and the premise of considering soil failure is proposed for the first time. Calculation model of horizontal ultimate bearing capacity of concrete expanded disc pile. The emphasis and innovation of this paper lies in the test method, which still adopts the visible test device of undisturbed soil. Because the general construction (construction) structure is usually in the environment of the interaction of vertical force and horizontal force, the test loading device has been repeatedly studied, tested and improved on the basis of the original vertical force loading device. The vertical force and horizontal force are loaded simultaneously. At the same time, on the basis of the existing experiments, the paper further improves the soil collecting device and method, and tries to obtain a more complete undisturbed soil sample. Because the whole process of the test is visible, through the observation and record of the soil failure process around the pile, the blank in the study of the soil failure state in the study of the expanded pile is made up. In this paper, the influence of plate diameter on the horizontal bearing capacity and soil failure state of concrete expanded pile will be improved, and the design theory of pile type will be improved, and the calculation method of horizontal bearing capacity of expanded disc pile will be enriched. It plays an important role in the application of concrete pile in building (construction) under horizontal force. At the same time, the improvement and innovation of test method provide reference for the research and development of pile foundation.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

【相似文献】