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Ultimate bearing capacity and failure mechanism on cyclic lateral loaded pile group

循环横向荷载群桩极限承载力及破坏机理

基本信息

批准号：
10650482
负责人：
ADACHI Toshihisa
金额：
$ 2.24万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650482/
关键词：
Pile foundation Pile group Bearing capacity Cyclic load Finite element method Elasto-plastic Cast-in-place pile せん断耐力遠心模型実験コンクリート群杭鋼管群杭

项目摘要

(1) In order to investigate the failure mechanism of the axially loaded concrete piles under cyclic lateral loading, the model of group pile is tested under centrifugal condition (50G). Mortar piles reinforced with piano wires and circular brass rings which are analogous to real cast-in-place concrete is about 2 mm. It was already found in the former tests that the damage occurred at the pile head first and when the magnitude of cyclic displacement became larger, damage of pile also took place at the depth under ground surface. In this paper, the influence of axial load on the failure behavior of the pile ground are investigated. After the test, cracks of piles are also observed.(2) Pile foundation in soft ground usually will be subjected to a lateral cyclic loading during an earthquake. In a major earthquake, it is reasonable to think that the mechanical behavior of a pile foundation and the surrounding ground is nonlinear. In recent year, the limit state design method became predominant in the design of foundations of toll bridges and other structures. The investigation on the mechanical behavior of the pile foundations subjected to lateral cyclic loadings up to an ultimate state, therefore, is very important to provide evidences for the designing method. In this paper, a real scale field test of 9-pile foundation, with a diameter of 1.2m, subjected to cyclic lateral loading up to an ultimate state, is simulated using a 3-dimensional elasto-plastic finite element analysis (DGPILE-3D). The nonlinear behavior of RC pile is simulated with an axial-force depend hysteretic model proposed in this paper. Meanwhile, the soil of the ground is simulated with Drucker-Prager model. The purpose of the paper is to provide an applicable numerical way of evaluating the mechanical behavior of a pile foundation subjected to cyclic lateral loading up to an ultimate state.

(1)为了研究混凝土轴压桩在水平循环荷载作用下的破坏机理，进行了离心力（50 G）作用下的群桩模型试验。用钢琴丝和圆形铜环加固的砂浆桩近似于真实的现浇混凝土，直径约为2 mm，在以往的试验中已经发现，桩的破坏首先发生在桩头，当循环位移幅值较大时，桩的破坏也发生在地表以下的深度。本文研究了轴向荷载对桩基破坏性状的影响。试验结束后，对桩身裂缝进行了观测。(2)软土地基中的桩基础在地震作用下通常会受到水平循环荷载的作用。在大地震中，桩基与周围地基的力学行为是非线性的。近年来，极限状态设计方法在收费桥梁及其它结构物的基础设计中占主导地位。因此，研究桩基在水平循环荷载作用下的极限状态下的力学行为，为桩基的设计方法提供依据是十分重要的。本文采用三维弹塑性有限元法（DGPILE-3D）对直径1.2m的9根桩基础在水平循环荷载作用下的极限状态进行了真实的现场试验模拟。本文提出了一种与轴力相关的钢筋混凝土桩的滞回模型。同时，采用Drucker-Prager模型对地基土进行模拟。本文的目的是提供一个实用的数值方法来评估桩基础的力学行为受到循环横向荷载，直到极限状态。