Experimental study on effects of lateral soil flow on group pile and its application to design procedure

侧向土流对群桩影响的试验研究及其在设计中的应用

基本信息

批准号：
16360234
负责人：
TOWHATA Ikuo
金额：
$ 9.02万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360234/
关键词：
liquefaction model test lateral pressure group pile ground flow shaking table sandy ground 群杭基礎粘性流体振動台砂地盤横荷重耐震設計

项目摘要

Model tests were conducted on a 1-G shaking table with a variety of group pile which was embedded in a liquefied sloping ground. Different from foregoing group pile tests with 4 or 9 constituent piles, the present study employed 36 or 121 piles in a square configuration.Upon shaking the model with different intensities and frequencies, the bending moment was recorded along the length of piles at several piles. Moreover, lateral ground displacement was studied by using data of embedded displacement transducers as well as distortion of soil markers in the ground surface. Records were taken of acceleration and pore water pressure as well. It was revealed that soil flows in the downslope direction upon liquefaction and large deformation occurs around piles. This large deformation makes it very difficult or even inappropriate to analyze the pile-soil interaction by conventional FEM analysis.The interpretation of bending moment data revealed that the magnitude of bending moment (and consequently the lateral earth pressure) takes the maximum value at the upstream and downstream ends of the pile foundation. This implies that the existence of piles in the upstream direction reduces the earth pressure in the downstream direction, which is called the Shadow Effects, and that, in the downstream end, the ground elevation difference, which is produced by the prevented soil flow by piles, creates significant lateral earth pressure on end piles. The shadow effects vary with the pile spacing ; the narrower spacing makes the shadow effects more remarkable.Finally, a retrofitting measure for existing group foundation was proposed. That is installation of additional piles on upstream and downstream sides of a foundation. The earth pressure due to flow of liquefied soil is borne by those additional piles and the load on the existing and important piles is mitigated. These findings were examined in a numerical model as well in which liquefied sand is modeled as a viscous liquid.

模型测试是在1克摇桌上进行的，并带有各种组桩，该桩嵌入在液化的倾斜地面中。与前述4或9个组成桩的群桩测试不同，本研究采用平方构型的36或121个桩。upon用不同的强度和频率摇动模型，沿着几个桩的桩的长度记录了弯矩。此外，通过使用嵌入式位移传感器的数据以及地面上土壤标记的变形来研究横向地面位移。记录也是加速和孔隙水压的记录。据显示，液化后的土壤流向下坡方向的流动，并且在桩周围发生较大的变形。这种较大的变形使通过常规FEM分析分析桩土相互作用变得非常困难甚至不合适。弯矩数据的解释表明，弯矩的幅度（因此，侧向地球压力）在上游时采用最大值和桩基础的下游末端。这意味着在上游方向存在堆的存在可降低下游方向的地球压力，这称为阴影效应，在下游的端，地面高程差异，这是由堆积的防止土壤流动产生的。，在末端产生明显的侧向压力。阴影效果随桩间距而变化。较窄的间距使阴影效果更加引人注目。在最后，提出了对现有小组基础的改造措施。那就是在粉底的上游和下游侧面安装其他桩。由于液化土壤流动引起的土压力由那些额外的桩承担，现有和重要的桩的负载得到缓解。这些发现也在数值模型中检查了，其中将液化的砂模型建模为粘性液体。

项目成果

期刊论文数量（20）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Model test on response of large pile group under lateral flow of liquefied sandy soil ground

液化砂土地基侧流作用下大型群桩响应模型试验

DOI：
发表时间：
2004
期刊：
Proc.Symp.on Behavior and Design of Piles Embedded in Liquefied Ground,Japanese Geotechnical Society
影响因子：
0
作者：
Sesov;V.;Towhata;L.;Gonzalez;M.;Ball;R.;Ishimatsu,S.
通讯作者：
Ishimatsu,S.

Development of Geotechnical Earthquake Engineering in Japan.

日本岩土地震工程的发展。

DOI：
发表时间：
2005
期刊：
Heritage Lecture, XVIth International Conference on Soil Mechanicsand Geotechnical Engineering, Osaka Vol.11
影响因子：
0
作者：
Towhata;Ikuo
通讯作者：
Ikuo

Experimental Study on Large Pile Group Response Subjected to Lateral Flow of Liquefied Ground.

液化地基侧流作用下大型群桩响应试验研究。

DOI：
发表时间：
2005
期刊：
Proc.TC4 Satellite Conference, Int.Conf.Soil Mechanics and Geotechnical Engineering, Osaka Vol.4
影响因子：
0
作者：
Sesov;V.;Towhata;I.;Gonzalez;M.;Ball;R.;Ishimatsu;S.
通讯作者：
S.

Experimental Study on Large Pile Group Response Subjected to Lateral Flow of Liquefied Ground

液化地基侧流作用下大型群桩响应试验研究

DOI：
发表时间：
2005
期刊：
Proc. TC4 Satellite Conference,Int.Conf.Soil Mechanics and Geotechnical Engineering,Osaka Vol.4
影响因子：
0
作者：
Sesov;V.;Towhata;L.;Gonzalez;M.;Ball;R.;Ishimatsu,S.
通讯作者：
Ishimatsu,S.

Performance of pile foundation in multi-layered liquefied soil.

多层液化土中桩基的性能