高填土作用下桥墩损伤机理与桥梁安全性能研究

发布时间：2018-08-25 07:48

【摘要】：在山区或重丘区修建桥梁时,沟谷地形十分常见,建设单位和施工单位为了节省成本,并考虑环保的原则,常常把桥下深沟作为路基的弃土场。这些回填土对桥墩一侧产生不平衡土压力,可能产生较大的侧向变形。造成桥墩偏位、产生裂缝,情况严重的桥墩将会被推倒。在实际工程中桥墩周围弃土现象十分常见,这些填土势必会对桥墩产生影响,造成桥墩严重偏位,开裂等现象。一般情况下,土体的不稳定状态引起的土体的侧移比土体的竖向沉降位移更为重要,尤其对于混凝土桥墩,因为在设计时,并未考虑桥墩承受水平荷载的能力,所以研究填土作用下桥墩的损伤机理,及其对全桥安全性能的影响是十分必要的。本文首先对填土侧移作用下桥墩桩的研究现状进行了总结和归纳,系统地介绍了土体侧移引起桥墩桩的抗阻作用,阐述了国内外一些有代表性的各种土压力作用下桩基的理论、试验及计算方法的成果。接着对有限元软件ABAQUS处理接触问题的理论进行了介绍,结合工程实例对填土作用下桥墩建立模型,分析了桥墩的受力情况和位移情况,以及产生裂缝的位置分布。此外还进一步研究了各种因素对桥墩受力的影响考虑了各种影响,如墩身几何条件、土层性质条件等等。本文旨在建立和完善高填土作用下桥墩的损伤机理,以及对全桥安全性能的危害,研究的主要内容包括以下几个方面： ①研究不均匀、后期高填土作用下桥墩的三维有限元模型如何建立。 ②依托实际工程,建立桥墩与填土的有限元模型,分析桥墩在高填土作用下的受力和变形特点,研究桥墩裂缝出现的原因,分析桥墩、桩基和承台的损伤机理,并结合实际观测的桥墩偏位情况,对有限元分析的结果进行验证。 ③利用有限元模型,分析高填土作用下单墩变形和受力的影响因素,如土体的容重、弹性模量、泊松比、内摩擦角和粘聚力；桥墩的弹性模量、直径及原地形坡度等对桥墩受力和变形的影响,分析各个因素对实际工程的意义。 ④建立全桥有限元模型,结合桥梁的病害,分析填土作用下桥墩偏移对全桥安全性能的影响,并提出有针对性的病害处治方法。
[Abstract]:In order to save the cost and consider the principle of environmental protection, the deep ditch under the bridge is often regarded as the abandoned soil field of the roadbed when the bridge is built in the mountainous area or the heavy hill area, the valley topography is very common, in order to save the cost and consider the principle of environmental protection. The backfill can cause unbalanced earth pressure on one side of bridge pier, which may result in large lateral deformation. Causes the pier to deviate, produces the crack, the serious condition bridge pier will be pushed down. The phenomenon of abandoned soil around the bridge pier is very common in the practical engineering, which will inevitably affect the bridge pier, causing serious deviation of the pier, cracking and so on. In general, the lateral displacement of the soil caused by the unstable state of soil is more important than the vertical settlement displacement of the soil, especially for the concrete pier, because the capacity of the pier to withstand horizontal load is not considered in the design. Therefore, it is necessary to study the damage mechanism of bridge piers and its influence on the safety performance of the bridge. In this paper, firstly, the research status of pier pile under lateral displacement of fill soil is summarized and summarized. The resistance of pile caused by soil lateral displacement is systematically introduced, and some representative theories of pile foundation under various kinds of earth pressure at home and abroad are expounded. The results of test and calculation methods. Then the theory of the finite element software ABAQUS to deal with the contact problem is introduced, and the model of bridge pier under the action of filling soil is established, and the stress and displacement of the pier and the location distribution of cracks are analyzed. In addition, the influence of various factors on the bearing force of the pier is further studied, such as the geometrical conditions of the pier, the properties of the soil, and so on. The purpose of this paper is to establish and improve the damage mechanism of bridge piers under the action of high fill, as well as the harm to the safety performance of the whole bridge. The main contents of the research include the following aspects: 1. How to establish the three-dimensional finite element model of bridge pier under the action of high fill in the later stage. (2) based on the actual engineering, the finite element model of pier and fill is established, and the characteristics of force and deformation of pier under the action of high fill are analyzed. This paper studies the causes of pier cracks, analyzes the damage mechanism of pier, pile foundation and cap, and verifies the results of finite element analysis combined with the observed deflection of bridge pier. 3 using the finite element model, the damage mechanism of bridge pier, pile foundation and abutment is analyzed. This paper analyzes the factors affecting the deformation and force of the pier under the action of high fill, such as bulk density, elastic modulus, Poisson's ratio, angle of internal friction and cohesion, and the influence of the elastic modulus, diameter and original topographic slope of the pier on the force and deformation of the pier. This paper analyzes the significance of each factor to the actual project. 4. The finite element model of the whole bridge is established. Combined with the bridge disease, the influence of pier offset on the safety performance of the bridge under the action of fill is analyzed, and the corresponding treatment method is put forward.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U447;U443.22

【参考文献】