变刚度调平在高层建筑设计中的应用

发布时间：2018-08-16 16:43

【摘要】：随着高层建筑的发展，桩基础得到了广泛的应用，它大大发挥了桩基的承载性能，而且取得了较好的经济效益和社会效益。然而传统的布桩方法是采用天然地基和均匀布桩，初始竖向支承刚度均匀分布，当设置于其上的刚度有限的基础（承台）受均布荷载作用时，由于土与桩、桩与桩的相互作用导致了地基或群桩的竖向支承刚度分布发生内弱外强的变化，其沉降会出现内大外小的蝶形分布，将引起自身和上部结构的附加弯、剪内力乃至开裂；基底反力会出现内小外大的马鞍形分布，将导致基础的整体弯矩增大。当上部结构为荷载与刚度内大外小的框架-核心筒结构时，蝶形沉降会更趋明显。为了避免上述的负面效应，通过变刚度调平概念设计，突破传统设计理念，调整地基或基桩的竖向支承刚度分布，促使建筑物的差异沉降减到最小，基础或承台内力和上部结构次应力显著降低，节约资源，提高建筑物的使用寿命，确保正常的使用功能。本文在前人研究的基础上，重点阐述了变刚度调平设计的的原理、方法和工程应用，总结了复合地基群桩沉降计算的方法，然后结合工程实例，运用变刚度调平概念设计和复合桩基沉降计算方法，并采用Flac3D软件分析了框架-核心筒结构变刚度调平后的沉降值，满足规范要求，减小了承台的附加内力。通过工程算例结果表明，对于框架-核心筒结构的高层建筑结构桩基，可以采取强化核心筒区域的桩基刚度，如增加桩长、改变桩距和桩径等，相对弱化外围框架的桩基刚度，如采用复合疏桩基础。这样可以有效的减小不均匀沉降，降低筏板的内力和上部结构的次应力，，并得到良好的经济效益。
[Abstract]:With the development of high-rise building, pile foundation has been widely used, which greatly exerts the bearing capacity of pile foundation, and obtains better economic and social benefits. However, the traditional method of pile layout is to adopt natural foundation and uniformly distributed pile, and the initial vertical support stiffness is uniformly distributed. When the foundation (cap) with limited stiffness is subjected to uniform load, the soil and pile are subjected to uniform load. The interaction between pile and pile leads to the change of internal and external strength of the vertical support stiffness distribution of foundation or pile group, and the settlement of the pile will appear the butterfly distribution, which will cause the additional bending, shear force and even cracking of itself and the superstructure. The reaction force of the base will appear the saddle shape distribution inside and outside, which will lead to the increase of the overall bending moment of the foundation. The butterfly settlement will become more obvious when the superstructure is a frame-core tube structure with large and small internal and external loads and stiffness. In order to avoid the negative effects mentioned above, through the variable stiffness leveling conceptual design, breaking through the traditional design idea, adjusting the vertical support stiffness distribution of the foundation or foundation pile, the differential settlement of the building is reduced to the minimum. The internal force of foundation or cap and the secondary stress of superstructure are obviously reduced, saving resources, improving the service life of buildings and ensuring the normal function. On the basis of previous studies, this paper focuses on the principle, method and engineering application of variable stiffness leveling design, summarizes the calculation method of pile group settlement on composite foundation, and then combines with engineering examples. By using variable stiffness leveling concept design and composite pile foundation settlement calculation method, and using Flac3D software, the settlement value of frame-core tube structure after variable stiffness leveling is analyzed, which meets the requirements of the code and reduces the additional internal force of the cap. The results of the engineering examples show that the pile foundation stiffness in the core tube region can be strengthened by strengthening the pile foundation of the high-rise building structure with frame-core tube structure, such as increasing the pile length, changing the pile spacing and the pile diameter, and weakening the pile foundation stiffness of the peripheral frame. Such as the use of composite pile foundation. In this way, the uneven settlement can be reduced effectively, the internal force of raft and the secondary stress of superstructure can be reduced, and good economic benefits can be obtained.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU972

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