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
关中唐十八帝陵是古代中国留给后代宝贵的历史文化遗产,千年以来帝陵遗址区水土流失现象加剧,破坏了帝陵景观。为了保护文化遗产,本文以某唐帝陵为对象,使用卫星和无人机影像产品,估算53年来司马道冲沟的发育速率,建立了帝陵遗址区的水...关中唐十八帝陵是古代中国留给后代宝贵的历史文化遗产,千年以来帝陵遗址区水土流失现象加剧,破坏了帝陵景观。为了保护文化遗产,本文以某唐帝陵为对象,使用卫星和无人机影像产品,估算53年来司马道冲沟的发育速率,建立了帝陵遗址区的水土流失体积-面积关系模型。结果表明:①遗址区受益于还林换草工程,坡耕地减少,草地林地增加。司马道下游林区NDVI指数达0.8,生态环境明显好转,水土流失等级转为轻度。②渭北旱塬地区,发育为卵状冲沟与其垂直面的切沟,周长与面积有良好的拟合关系。③唐帝陵遗址区的沟道发育模型,面积和体积之间有良好的幂函关系,即y=0.0405 x 1.4936,决定系数R 2=0.82,53年来的切沟年发育为0.36 m/a。可将上述模型作为渭北旱塬地区沟道发育模型。④遗址区水土流失和土壤沉积体积比率为38.5∶1,产生的侵蚀和土壤沉积面积比率为11.5∶1。展开更多
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.
文摘关中唐十八帝陵是古代中国留给后代宝贵的历史文化遗产,千年以来帝陵遗址区水土流失现象加剧,破坏了帝陵景观。为了保护文化遗产,本文以某唐帝陵为对象,使用卫星和无人机影像产品,估算53年来司马道冲沟的发育速率,建立了帝陵遗址区的水土流失体积-面积关系模型。结果表明:①遗址区受益于还林换草工程,坡耕地减少,草地林地增加。司马道下游林区NDVI指数达0.8,生态环境明显好转,水土流失等级转为轻度。②渭北旱塬地区,发育为卵状冲沟与其垂直面的切沟,周长与面积有良好的拟合关系。③唐帝陵遗址区的沟道发育模型,面积和体积之间有良好的幂函关系,即y=0.0405 x 1.4936,决定系数R 2=0.82,53年来的切沟年发育为0.36 m/a。可将上述模型作为渭北旱塬地区沟道发育模型。④遗址区水土流失和土壤沉积体积比率为38.5∶1,产生的侵蚀和土壤沉积面积比率为11.5∶1。
