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Study on the allowable deformation of structures in liquefied grounds and appropriate measures against liquefaction

液化地基结构允许变形及防液化措施研究

基本信息

批准号：
14550499
负责人：
YASUDA Susumu
金额：
$ 1.22万
依托单位：
Tokyo Denki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550499/
关键词：
Liquefaction Earthquake Seismic design Seismic preparedness Sandy soil 砂地盤直接基礎地中構造物

项目摘要

Liquefaction causes deformation of structures such as settlement of buildings and floatation of manholes. In current design procedure for liquefaction, however, the occurrence of liquefaction is judged only. Deformation of the structures is not evaluated. In the design for Level 2 earthquake motion, which has been introduced recently in new design codes after the 1995 Hyogoken-nambu earthquake, it is necessary to evaluate the deformation because many current countermeasures can not prevent the occurrence of liquefaction. Then, in this research, appropriate evaluation methods for liquefaction-induced deformation of structures and allowable deformation in liquefied grounds were studied by conducting several site investigations, shaking table tests and residual deformation analyses. Simple measure methods against the settlement of houses and the floatation of conduits were developed also. Effectiveness of the developed methods were confirmed by carrying out shaking table testes and seismic response analyses. Main conclusions derived from the research were as follows :1.A site investigation on the liquefaction-induced settlement of timer houses during the 2000 Tottoriken-seibu earthquake showed that the allowable angle of tilting was almost 1/100.2.Settlement of tanks and floatation of buried conduits can be evaluated by a residual deformation analysis "ALID." Effectiveness of ground improvement by compaction was also evaluated by this analysis.3.Effectiveness of gravel drain method can be evaluated by focusing on the settlement of structures even though the improved ground is liquefied under Level 2 earthquake motion.4.A simple countermeasure method by attaching brads to buried conduits was effective to prevent liquefaction-induced floatation.5.A lot of sewage manholes floated up during the 2003 Tokachi-oki earthquake. Detailed site investigation revealed that the floatation induced due to the liquefaction of backfilled soils.

液化会引起建筑物的变形，如建筑物的沉降和检查井的上浮。然而，在现行的液化设计程序中，仅对液化的发生进行判断。未对结构的变形进行评估。在1995年兵库县南部地震后新的设计规范中引入的2级地震运动设计中，由于目前的许多对策无法防止液化的发生，因此有必要评估变形。然后，在本研究中，适当的评估方法，液化引起的变形和允许变形的结构进行了多次现场调查，振动台试验和残余变形分析研究。提出了防止房屋沉降和管道上浮的简易措施。通过振动台试验和地震反应分析，验证了本文方法的有效性。通过对2000年鸟取县西武地震中水箱房的沉降观测，得出水箱房的允许倾斜角度约为1/100。“通过这项分析还评估了通过压实进行地基加固的有效性。3.即使在2级地震运动下加固的地基液化，也可以通过关注结构的沉降来评估砾石排水法的有效性。4.通过在埋地管道上附加钉的简单对策方法可以有效地防止液化。5.在2003年十胜大地震中，许多下水道的沙井浮了起来。详细的现场调查显示，浮起是由于回填土的液化引起的。