1 Preface In the northern and northwestern parts of China, quite a large portion of area, approximately 630,000 km^2, is covered by loess and loess-liked soils. The loess thickness ranges from several meters to severa...1 Preface In the northern and northwestern parts of China, quite a large portion of area, approximately 630,000 km^2, is covered by loess and loess-liked soils. The loess thickness ranges from several meters to several hundred meters along the river’s terraces to those geomorphologic plateaus. In geology, "China Loess" has become a geologic term, because the loess in China has evolved with the widest distribution and greatest thickness in the world, and is also a typical and significant deposit in Quaternary Period.展开更多
The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6)...The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively.展开更多
文摘1 Preface In the northern and northwestern parts of China, quite a large portion of area, approximately 630,000 km^2, is covered by loess and loess-liked soils. The loess thickness ranges from several meters to several hundred meters along the river’s terraces to those geomorphologic plateaus. In geology, "China Loess" has become a geologic term, because the loess in China has evolved with the widest distribution and greatest thickness in the world, and is also a typical and significant deposit in Quaternary Period.
基金financially supported by National Natural Science Foundation of China (No.51478444 & No.41472297)
文摘The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively.
