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EVALUATION OF DYNAMIC SOIL-PILE-STRUCTURE INTERACTION DURING SOIL LIQUEFACTION AND CYCLIC MOBILITY

土壤液化和循环流动过程中动态土-桩-结构相互作用的评估

基本信息

批准号：
07455216
负责人：
TOKIMATSU Kohji
金额：
$ 3.2万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455216/
关键词：
Pile Interaction Ground displacement Whincler foundation Centrifugal model test Earthquake Bending moment

项目摘要

The conditions causing soil liquefaction and resulting damage to building foundations in the 1995 Hyogoken-Nambu earthquake are examined. It is shown that possible causes fo the foundation damage include : (1) horizontal forces and overturning moments imposed on the foundation from the superstructures, (2) kinematic forces acting on deep foundations due to shear deformation of soils, (3) reduction in bearing capacity due to ground failures including liquefaction, and (4) lateral spreading.Both failure and deformation modes are examined using a borehole camera and a slope-indicator for prestressed concrete piles of buildings that experienced liquefaction-induced ground displacement during the 1995 Hyogoken-Nambu earthquake. It is shown that the damage is concentrated at the interface between liquefied and non-liquefied layrs, suggesting the significant effect of ground displacement on pile damage.Centrifuge shaking table tests are conducted on a soil-pile-structure model to investigate the effects of ground displacement and inertia force from the superstructure on stresses in piles during soil liquefaction. It is shown that the ground displacement and inertia force are in phase if the natural period of the structure is less than that of the soil deposit, whereas they are out of phase if the natural period of the structure is greater than that of the soil deposit.An analytical model is then proposed in which a group of piles connected with the same foundation is subjected to lateral ground displacement and inertia force, and the stress and displacement of the piles are calculated. The computed failure and deformation modes agree reasonably well with the field observations, confirming that the proposed analytical model could be effectively used to estimate stresses in piles during soil liquefaction.

研究了1995年日本南部地震中引起土壤液化和对建筑物地基造成破坏的条件。结果表明，地基破坏的可能原因包括：(1)上部结构施加在地基上的水平力和倾覆力矩，(2)土的剪切变形作用于深层地基的运动力，(3)地基液化等地基破坏导致的承载力降低，以及(4)横向扩展。通过土体-桩-结构模型的离心式振动台试验，研究了土体液化过程中地基位移和上部结构惯性力对桩体内应力的影响。结果表明，当结构的自振周期小于土体的自振周期时，地基位移和惯性力是同步的，而当结构的自振周期大于土体的自振周期时，地基的位移和惯性力是异相的，并建立了与同一基础相连的一组桩在水平地基位移和惯性力共同作用下的解析模型，计算了桩的应力和位移。计算的破坏和变形模式与现场观测结果吻合较好，验证了所提出的分析模型可以有效地用于估算土体液化过程中桩体内的应力。