分体式沉井水平荷载作用下长期力学行为分析

发布时间：2018-01-12 22:16

本文关键词：分体式沉井水平荷载作用下长期力学行为分析　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：分体式沉井是一种新型的基础形式,本课题依托国家973计划课题“特大跨桥梁全寿命灾变控制与性能设计的基础研究”子课题“复杂环境下深水基础承载行为演化与长期性能设计”,以室内模型试验为基础,研究了分体式沉井在水平荷载作用下的长期力学行为,开展的主要内容和成果如下：1、分体式沉井由于前、后两个沉井的协同作用,相比于等体积的单体沉井大大提高了基础的抗倾覆能力,在相同的水平荷载作用下,基础的转动中心下移,使得分体式沉井以平动为主伴随有轻微转动,而普通单体沉井有较明显的倾覆；2、设计并进行了砂土中分体式沉井前、后沉井之间合理间距选择的室内模型试验,发现前、后两个沉井之间的合理间距约为荷载作用方向单体小沉井边长的2倍；3、通过室内饱和粘土中的全模型试验,发现分体式沉井水平荷载的影响范围约为荷载作用方向基础长度(该长度包含两个沉井之间的土体长度)的2倍；4、设计并进行了重塑饱和粘土中分体式沉井的全模型和半模型试验,采用传统与薄膜压力传感器相结合的试验方法以及PIV技术,研究并分析了水平荷载长期作用下,分体式沉井的水平位移、前后两个沉井侧壁与底部的土压力分布情况以及它们随时间的演变规律,为建立分体式沉井水平荷载长期作用下考虑土体蠕变效应的设计理论提供参考；5、通过对水平长期试验数据的拟合,得出考虑土体蠕变效应,分体式沉井计算理论中涉及到的与水平荷载大小、荷载作用时间、沉井深度有关的P-Y曲线;6、建立了分体式沉井的简化计算理论,通过对水平荷载和约束弯矩的分配将分体式沉井拆分为两个单体沉井,对单体沉井考虑沉井的计算宽度,利用上述拟合得到P-Y曲线并结合Lpile软件和Matlab编程,对荷载作用不同时间后,分体式沉井的水平承载性能进行计算；7、运用该理论计算方法对一工程算例进行计算,以适应工程的需要,表明本文提出的解决方法有一定的实用意义。
[Abstract]:Split caisson is a new basic form. This subject relies on the national 973 project "the basic research of the catastrophic control and performance design for the whole life of large span bridge". The sub-project "the evolution of bearing behavior and long-term performance design of deep water foundation under complex environment". Based on the laboratory model test, the long-term mechanical behavior of the split caisson under horizontal load is studied. The main contents and results are as follows: 1. Compared with the single caisson of equal volume, the anti-overturning ability of the foundation is greatly improved. Under the same horizontal load, the rotation center of the foundation moves down, which makes the split caisson mainly with the translational motion accompanied by slight rotation. The common single caisson has obvious overturn. 2. The laboratory model test of the reasonable distance between the split caisson and the rear caisson in sand is designed and carried out. The reasonable distance between the latter two caisson is about 2 times as long as the side length of the small caisson in the direction of load action. 3. Through the whole model test in saturated clay in laboratory, it is found that the influence range of horizontal load in split caisson is about 2 times as long as the foundation length in the direction of load action (including the soil length between two caisson wells). 4. The full-model and semi-model tests of split caisson in remolded saturated clay were designed and carried out. The traditional test method combined with membrane pressure sensor and PIV technology were adopted. This paper studies and analyzes the horizontal displacement of the split caisson, the distribution of the earth pressure on the side wall and the bottom of the two caisson wells and their evolution with time under the long-term action of horizontal load. It provides a reference for the design theory of considering the creep effect of soil under the horizontal load of split caisson for a long time. 5. By fitting the long-term horizontal test data, the P-Y curves related to horizontal load, loading time and depth of caisson are obtained considering the creep effect of soil mass and the calculation theory of split caisson. 6. The simplified calculation theory of split caisson is established. Through the distribution of horizontal load and constrained bending moment, the split caisson is divided into two single caisson, and the calculation width of single caisson is considered. The P-Y curve is obtained by the above fitting and combined with Lpile software and Matlab programming, the horizontal load-bearing performance of the split caisson is calculated after different loading time. 7. The method is used to calculate an engineering example in order to meet the needs of the project, which shows that the proposed method has certain practical significance.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.131

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