Field Investigation on Dynamic Behavior of Soil and Building Structures in the Near-Fault Region of the 1999 Chi-Chi, Taiwan Earthquake

本计画的目的是了解在1999年台湾集集地震现场调查的基础上，在近断层区域建造的结构的破坏机制，其中我们有宝贵的强地面运动，最近的高分辨率地震仪网络观察。为此，我们临时部署了一个余震观测网络，并对土壤结构和建筑结构进行了微动监测，以了解它们的动力特性。我们首先根据近断层地区场地的地面特性来调查观测到的强震，并估计没有观测记录的场地的强震，在2000年我们在台中地区进行了为期两周的微动台阵和单站调查，以描绘台中盆地的S波速度结构。同时也量测了台中地区典型建筑物的地震动。然后，我们进行了非线性分析，建立了日本的建筑模型，以了解在近断层区域观测到的强烈运动的破坏潜力。结果表明，在近断层区观测到的强震，除两条记录在中间周期范围（101 s）内与科比的记录具有相同的谱级外，其余大部分没有表现出强的破坏潜势。2001年我们在台北盆地进行了地下S波结构的探测，如果在不久的将来发生大的地震，它可能会造成巨大的破坏。根据这些资料，我们准备评估台湾的结构的破坏潜力，我们可以比较台湾和日本的建筑物的破坏潜力。

The purpose of the project is to understand the damage mechanism of structures built in the near-fault regions based on the field investigation of the 1999 Chi-Chi, Taiwan, earthquake, in which we have invaluable strong ground motions observed by a recent network of high resolution seismometers. To this end we deployed temporarily an aftershock observation network and we also conducted microtremor observeation for both soil structures and building structures to understand their dynamic behavior. We first investigate observed strong motions based on the ground property of the sites in a near-fault region and estimate strong motions for sites without observed records.In the year 2000 we conducted for two weeks microtremor array and single-station survey in the Taichung area in order to delineate the S-wave velocity structure of the Taichung Basin. Microtremors in typical buildings in Taichung were also measured. We then performed nonlinear analysis of building models established for Japan to understand the damage potential of the observed strong motions in the near-fault region. It turns out that most of the strong motions observed in the near-fault area do not show strong damage potential except for two records, which show the same spectral levels in the intermediate period range (〜1 sec) with the records in Kobe. In the year 2001 we explored underground S-wave structures in the Taipei Basin, which may have much devastating damage if a big event happen in near future. Based on these information we are ready to evaluate damage potential of the structures in Taiwan and we can compare damage potential of buildings in Taiwan and Japan.