土体侧移对管桩竖向承载性能的影响

发布时间：2019-04-27 09:04

【摘要】：管桩在设计之初主要承受竖向荷载,并具备较高的竖向承载力,而水平承载力则相对较弱。近年来,土体侧移导致管桩承载力破坏的事故日益增多,为防止此类建筑病害的发生,提高管桩在土体侧移作用下的安全性,本课题通过室内模型试验及数值模拟分析,对土体侧移条件下的管桩基础承载性状进行研究,具体如下:首先,通过对已有的相关研究进行论述,在总结相关研究的基础上,提出本课题的研究路线及试验方法。其次,通过室内模型试验对管桩竖向承载性能进行分析,探讨不同土体加载位置、土体侧移加载量等因素对管桩竖向承载性能的影响并得出:(1)土体侧移对桩周土体起到挤密和塑性破坏两方面的效果;(2)当桩顶具有较大的竖向荷载时,土体侧移条件下单桩会突然发生破坏,失去竖向承载性能;(3)土体侧移加载点较小时,管桩基础竖向承载性能有小幅度的提升,表明土体挤密效应大于土体塑性破坏。然后,利用FLAC3D对土体侧移条件下单桩进行模拟,分别从土体侧移大小、管桩内径大小、桩顶既有荷载及土体侧移深度四个方面进行讨论,对桩身侧移、桩身弯矩、桩身轴力及负摩阻力进行了分析,认为土体侧移条件下的管桩,桩身下部产生负摩阻力,应加强桩身抗拉强度设计;对于桩身抗侧移要求严格的管桩,应严格控制土体侧移深度。最后,对群桩基础进行模拟分析,主要讨论土体侧移量、土体侧移模式、土体侧移加载位置、桩身刚度等因素对管桩承载性状的影响。并对群桩中各桩桩身受力性状进行分析,结果表明:土体侧移条件下,前排桩桩身呈上浮趋势,桩身受拉,后排桩桩身下沉,桩身压力增大;各桩桩身位移大小及趋势基本一致;桩顶既有荷载使各管桩桩身弯矩增大;对于不同侧移模式下各桩承载性状应具体分析。
[Abstract]:At the beginning of design, pipe pile mainly bears vertical load and has higher vertical bearing capacity, while horizontal bearing capacity is relatively weak. In recent years, the accidents of soil lateral displacement leading to the failure of bearing capacity of pipe pile are increasing day by day. In order to prevent the occurrence of this kind of building disease and improve the safety of pipe pile under the action of soil lateral displacement, this subject adopts indoor model test and numerical simulation analysis. The bearing behavior of pipe pile foundation under the condition of lateral displacement of soil is studied as follows: firstly, through the discussion of the existing related research, on the basis of summarizing the related research, the research route and test method of this subject are put forward. Secondly, through the indoor model test, the vertical bearing capacity of pipe pile is analyzed, and the loading position of different soil mass is discussed. The influence of soil lateral load and other factors on the vertical bearing capacity of pipe pile and the following conclusions are drawn: (1) the lateral displacement of soil has two effects on compaction and plastic failure of soil around the pile; (2) when the pile top has a large vertical load, under the condition of lateral soil movement, the single pile will suddenly destroy and lose the vertical bearing capacity; (3) when the loading point of lateral displacement of soil is small, the vertical bearing capacity of pipe pile foundation is improved by a small extent, which indicates that the compaction effect of soil is greater than plastic failure of soil mass. Then, using FLAC3D to simulate the order pile under the condition of lateral displacement of soil, this paper discusses the lateral displacement of pile, the inner diameter of pipe pile, the existing load of pile top and the depth of lateral displacement of soil, and discusses the lateral displacement of pile body and the bending moment of pile body. The axial force and negative friction resistance of the pile body are analyzed. It is considered that the pipe pile under the condition of lateral displacement of the soil body produces negative friction resistance under the condition of the pile body, and the tensile strength design of the pile body should be strengthened. The lateral displacement depth of soil should be strictly controlled for pipe piles with strict resistance to lateral displacement. Finally, the influence of soil lateral displacement, soil lateral displacement mode, soil lateral loading position, pile stiffness and other factors on the bearing behavior of pipe pile is discussed by simulation and analysis of pile group foundation. The results show that under the condition of lateral displacement of soil, the pile body of the front row is upward, the pile body is pulled, the pile body of the rear row pile is sinking and the pressure of the pile body is increased. The displacement size and trend of each pile body are basically the same, the existing load on the top of the pile increases the bending moment of each pipe pile body, and the bearing behavior of each pile under different lateral displacement modes should be analyzed in detail.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

【参考文献】