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

该项目的目的是在1999年台湾集集地震现场调查的基础上，了解近断层地区建筑的破坏机制，在这次地震中，我们通过最近的高分辨率地震仪网络观测到宝贵的强地面运动。为此，我们临时部署了余震观测网，并对土壤结构和建筑结构进行了微震观测，了解其动力特性。我们首先根据近断层地区场址的地面性质研究观测到的强运动，并对没有观测记录的场址估计强运动。2000年，为了圈定台中盆地的横波速度结构，我们在台中地区进行了为期两周的微震阵和单站测量。台中地区典型建筑物的微震也进行了测量。然后，我们对为日本建立的建筑模型进行非线性分析，以了解在近断层区域观测到的强运动的破坏潜力。结果表明，在近断裂带观测到的强运动中，除有2个记录与神户记录在中间周期范围（~ 1秒）表现出相同的谱级外，大部分强震都没有表现出强烈的破坏潜力。2001年，我们在台北盆地勘探了地下s波结构，如果在不久的将来发生大事件，这些地下s波结构可能会造成很大的破坏性破坏。基于这些信息，我们准备评估台湾建筑物的潜在破坏，我们可以比较台湾和日本建筑物的潜在破坏。

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.