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Pile groups under cyclic horizontal loading

水平循环荷载下的群桩

基本信息

批准号：
321719367
负责人：
Professor Dr.-Ing. Oliver Reul
金额：
--
依托单位：
Fachgebiet Geotechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/321719367?language=en
关键词：
Pile groups under cyclic horizontal

项目摘要

According to EA-Pfähle (EA-P) (DGGT 2012) cyclic loading is defined as a repetitive loading of piles where forces of inertia acting on the pile-soil-system do not need to be considered. Cyclic loading of pile foundations is of importance in various fields of civil engineering such as offshore- and onshore- wind turbines or structures for transport infrastructure. For offshore wind turbines mainly monopiles (i.e. single piles with large diameters) or jacket-structures with large pile spacing (i.e. interactions between piles are of minor importance) are constructed. However, bridge abutments are frequently founded on groups of piles with relatively small pile spacing. Foundations of this type comprising a number of interacting piles subsequently will be termed pile groups. Cyclic loadings are caused for example by wind and waves (offshore wind turbines) or temperature induced constraints (integral bridges without joints and bearings).According to EA-P there is only limited knowledge available for piles under cyclic loading. To consider cyclic temperature induced constraints for integral and semi-integral bridges, frequently more or less arbitrarily chosen reduction coefficients are applied in the design process. It is therefore the main objective of the project to carry out a fundamental study on the bearing behaviour of pile groups under cyclic horizontal loading and to evaluate the results qualitatively as well as quantitatively. Within this study the influence of parameters such as subsoil conditions, pile group geometry and loading condition are to be investigated experimentally and numerically. Pile group geometries and loading conditions are to be based on configurations typical for integral and semi-integral bridges.In detail the following topics are to be treated:- Identification of the main parameters influencing the bearing behaviour of pile groups under cyclic horizontal loading.- Review of the reduction coefficients documented in the EA-P for the distribution of pile loads and Winkler modulus within a pile group under static loading and adjustment of these coefficients for significant cyclic loading.- Development of an analysis model based on the Enhanced Strain Wedge Model (ESWM) by Tasan (2011) which allows the determination of the following parameters: + Accumulation of the horizontal displacement at the pile head. + Distribution of the Winkler modulus along the pile shaft for the various piles within the pile group. + Distribution of bending moment and shear force along the pile shaft for the various piles within the pile group.

根据EA-PFähle(EA-P)(DGGT 2012)，循环荷载被定义为桩的重复荷载，其中不需要考虑桩-土-体系的惯性力。桩基础的循环荷载在各种土木工程领域中都很重要，例如海上和陆上风力涡轮机或交通基础设施的结构。对于海上风力发电机，主要是建造单桩(即大直径的单桩)或大桩间距的导管架结构(即桩间相互作用次要)。然而，桥梁桥台往往建立在桩间距相对较小的群桩上。由多个相互作用的桩组成的这种类型的基础随后将被称为群桩。循环荷载是由风和波浪(海上风力涡轮机)或温度引起的约束(无接头和支座的整体桥)引起的。根据EA-P，对于循环荷载下的桩只有有限的知识可用。为了考虑整体式和半整体式桥梁的循环温度约束，在设计过程中经常或多或少地采用任意选取的折减系数。因此，对循环水平荷载作用下群桩的承载性状进行基础性研究，并对其结果进行定性和定量的评价，是本项目的主要目标。在本研究中，将对地基条件、群桩几何形状和荷载条件等参数的影响进行试验和数值研究。群桩几何形状和荷载条件应以整体式和半整体式桥梁的典型构型为基础。将详细处理以下主题：-确定在循环水平荷载下影响群桩承载性能的主要参数。-回顾EA-P中记录的关于静载下桩荷载分布和群桩内Winkler模数的折减系数，并针对显著的循环荷载对这些系数进行调整。-基于Tasan(2011)的增强型应变楔形模型(ESWM)开发分析模型，该模型允许确定以下参数：+桩头水平位移的累积。+群桩内不同桩的文克勒模数沿桩轴的分布。+群桩内各桩的弯矩和剪力沿桩身的分布。