報告書番号

U99038

タイトル（和文）

台湾・花蓮地点大規模耐震実証試験研究 --直交異方性弾性体モデルを用いた動的シミュレーション解析--

タイトル（英文）

The Hualien Large-Scale Seismic Test for Soil-Structure Interaction Research, ‐ Dynamic simulation analysis using orthotropic elastic body ‐

概要 （図表や脚注は「報告書全文」に掲載しております）

大地震時の地盤と構造物の相互作用を調べるため，『花蓮プロジェクト』と呼ばれる国際共同研究が現在進行している．このプロジェクトの模型構造物の基礎地盤は礫地盤であり，正確な地震時応答の予測をするために詳細な地盤調査・試験が行われた．動的シミュレーション解析の精度向上を目的として，既報告書においては砂礫層の応力・ひずみ関係を直交異方性弾性体で表し，簡略な検討によりその有効性を定性的に明らかにした．更にその有効性を定量的に評価するため，本報告では速度検層，強制振動実験ならびに地震観測による実測結果と計算結果を比較するなどして以下の成果を得た． （１）クロスホール法速度検層により得られたせん断波速度に見られる方位依存性を説明できた．（２）ダウンホール法速度検層により得られたせん断波速度が大別して２種類になることが説明できた．（３）模型建屋の強制振動実験結果ならびに地震観測結果をシミュレートできた．

概要 （英文）

A Hualien Large-Scale Seismic Test (HLSST) program is under way to investigate Soil-Structure Interaction during large earthquakes in the field of Hualien, a high seismic region in Taiwan. In the HLSST, predictive and correlative simulation analyses of forced vibration tests for 1/4-scale model building and earthquake observation records were conducted. Thus, extensive geotechnical investigation including velocity logging and sampling by means of in-situ freezing technique were conducted for accurate simulation analysis. According to the simulation results, the results of forced vibration tests for the model building with backfill and without backfill could not be simulated with sufficient accuracy because of the anisotropy and heterogeneity of the gravelly soil layer just beneath the model building. In the previous report, anisotropic behavior of the gravelly soil layer was modeled by orthotropic elastic body to improve the accuracy of dynamic response analysis. In this report, firstly, calculation was conducted to reproduce the results of velocity logging conducted for the gravelly soil layer just beneath the model structure using the orthotropic elastic body model. Secondly, three dimensional dynamic simulation analyses of forced vibration tests and earthquake response were conducted using the orthotropic elastic body model. The following conclusions were drawn through this report. (1) The azimuth dependency of the shear wave velocity measured by the cross-hole velocity logging can be expressed by the orthotropic elastic body model. (2) It can be explained by the orthotropic elastic body model that shear wave velocities measured by down-hole velocity logging were divided into two groups. (3) The resonance curves of horizontal forced vibration tests of the model building with or without backfill can be successfully simulated by the orthotropic elastic model. Moreover, results of earthquake observation can be simulated by the orthotropic elastic model. (4) An outline of the procedure for investigating an anisotropic gravelly soil layer to determine parameters of the orthotropic elastic model was proposed.

報告者

キーワード