【作者】 易笃韬；

【导师】 邵旭东；

【作者基本信息】 湖南大学 ， 桥梁与隧道工程， 2004， 硕士

【摘要】 桩基断裂、台身开裂、台后路面长期连续下沉等现象是软土地区的桥梁经常出现的病害,严重影响了交通的正常运营。其原因是由于软土的承载能力很低,而且具有非常明显的流变特性,在台后路基的填筑和运营阶段车辆的行使等不平衡竖向荷载的作用下,软土原有的平衡状态受到破坏,引起较大的粘塑性变形,从而对桩基造成了较大的挤压荷载,并通过桩基带动桥台发生变形,由此产生一系列的结构病害。当附加竖向荷载较大时,软土的粘塑性变形和对桩身产生的流变力将随时间而增长。本文就软土地基桥台的分析方法进行了较深入的分析与研究。 首先,在前人研究和现场检测的基础上,全面分析了软土地基桥台的基本受力特性,并提出软土地基桥台的受力分析关键是如何考虑软土层的存在对桥台结构的影响,为建立有限元计算模型奠定了理论基础; 其次,在总结分析基于模型理论的软土流变特性的基础上,分析了移动土体对桩基的横向附加荷载的理论计算公式在软土地基桥台计算中的适用条件,建立了简化的杆系有限元计算模型,并利用与离心试验的对比计算证明了计算模型的正确性。然后通过对工程实例的分析指出了软土地基桥台病害的原因。 最后,利用前面简化的计算模型对设计中影响软土地基桥台受力的因素进行了分析,由此得到了一些有益的结论。更多还原

【Abstract】 The phenomenon, such as piles failure, abutment rupture, road surface behind abutment appearing settlement in succession for a long time after construction, are common damage of the abutment which constructed on the soft clay, and which have influenced the normal running of the traffic seriously. Its reason is because the bearing capacity of the soft clay is very low, and has very obvious rheological characteristics. The already existing balance state of the soft soil layer will be destroyed by the unsymmetrical and vertically additional loads which caused by the construction of the retained fill behind the abutment and the transportation of the vehicle, and thus results in great visco-plastic deformation in the soft clay. It will induce great extrusion load on the piles of the abutment. Analysis and study on the analytical method of the abutment which constructed on the soft clay has been performed in this paper.Firstly, on the basis of the forerunners’ research and local inspection, analysis the fundamental mechanic character of the abutment constructed on soft clay overall, and point out that how to consider the influence to the abutment construction caused by the existence of soft soil layer is the key point to the mechanic analysis of the abutment constructed on the soil clay. It establishes the groundwork in theory for setting up finite element calculation model.Secondly, on the basis of summarizing and analyzing the rheological characteristics of the soft clay based on theory of the model, the suitable conditions of the theoretical formula to calculate the additional lateral load on piles under abutment caused by the lateral movement of the soft soil has been analyzed. Set up a simplified finite beam element calculation model, and prove the exactness of calculating model by comparing to the results of the centrifuge test. Then point out the reason of the disease of the abutment constructed on the soft clay through an analysis of project instance.Finally, the factors which influence the mechanic character of the abutment in the design has been analyzed by utilizing the simplified calculation model, therefore has got some helpful conclusions.更多还原