长期水平荷载作用下沉井基础的变位特性研究

发布时间：2018-06-14 10:20

本文选题：沉井 + 长期水平荷载　；参考：《东南大学》2015年硕士论文

【摘要】：沉井基础是悬索桥锚碇中常用的重力式基础,过去多建造于坚硬岩层或土层上,利用其自重在基础底面产生的摩擦力来抵抗主缆的巨大拉力。近年来,多座悬索桥建造于深水软弱土层地区,因为软土强度较低且具有时变特征,沉井基础在水平荷载作用下的变位会随时间不断变化,目前沉井基础在软土中的水平承载性能研究尚不完善,设计理论缺乏可靠依据,对其展开研究显得尤为必要。论文的主要工作内容如下：首先,根据研究计划制定了相应实验方案,并进行了室内缩尺模型实验。实验分为四组,分别是一组短期预实验、两组长期全模型实验和一组长期半模型实验。短期预实验测得了沉井极限水平承载力并为长期实验方案设计提供可靠依据。随后,通过对两组长期全模型实验结果的分析,得到了沉井周围土压力、沉井自身变位和沉井前侧土体表面水平位移随荷载和时间变化的分布规律；半模型实验则利用PIV技术研究了沉井前侧土体的流变特性。最后,以理想弹塑性p-y曲线为基础,提出了可以考虑埋深、时间和荷载水平影响的p-y曲线模型,并给出相应计算公式。该公式计算结果、实验结果、ABAQUS分析结果吻合较好。应用本文计算方法进行工程实例分析,计算精度能满足工程需要,对实际工程的设计与应用具有较强的参考价值。
[Abstract]:Caisson foundation is a kind of gravity foundation commonly used in suspension bridge Anchorage. In the past, the caisson foundation was built on hard rock or soil layer, and the friction produced by its deadweight on the bottom of the foundation is used to resist the great tension of the main cable. In recent years, many suspension bridges have been built in deep water soft soil layers. Due to the low strength and time-varying characteristics of soft soil, the displacement of caisson foundation under horizontal load will change with time. At present, the research on horizontal bearing capacity of caisson foundation in soft soil is not perfect, and the design theory is lack of reliable basis, so it is necessary to carry out research on it. The main work of this paper is as follows: firstly, the corresponding experimental scheme is made according to the research plan, and the indoor scale model experiment is carried out. The experiment was divided into four groups: one group of short-term pre-experiment, two groups of long-term full model experiment and one group of long-term semi-model experiment. The limit horizontal bearing capacity of the caisson is measured by short-term pre-test and the reliable basis is provided for the design of long-term experimental scheme. Then, by analyzing the experimental results of two groups of long-term models, the distribution of the earth pressure around the caisson, the displacement of the caisson itself and the horizontal displacement of the soil surface in front of the caisson with load and time are obtained. The rheological properties of the soil in front of the caisson are studied by using PIV technique in the semi-model experiment. Finally, based on the ideal elastoplastic p-y curve, a p-y curve model considering the influence of buried depth, time and load level is proposed, and the corresponding formulas are given. The results of the formula are in good agreement with the results of Abaqus analysis. The application of this method to the analysis of engineering examples shows that the accuracy of calculation can meet the needs of engineering and has a strong reference value for the design and application of practical projects.
【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】：U448.25;U443.131

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