Based on a detailed environmental investigation of the whole Qingshui Stream catchments,samples of water and surface sediments were collected at 15 different places from the upper to the lower reaches of Qingshui Stre...Based on a detailed environmental investigation of the whole Qingshui Stream catchments,samples of water and surface sediments were collected at 15 different places from the upper to the lower reaches of Qingshui Stream,and samples of suspended matter were obtained by filtrating the water samples. The concentrations of heavy metals (Cd,Cu and Zn) were measured in filtered water,suspended matter,and surface sediment by ICP-AES. The results show that the concentrations of the three heavy metals in filtered water are 0.18,6.6 and 17.67 μg/L,lower than that of the Fresh Water Quality Criteria (US EPA) and those of the plain urban rivers,but the contents of Cd,Cu and Zn are much higher than the mean values of rivers in the world and the background value in Jialing River basin. The heavy metals concentrations in the suspended matter from Qingshui Stream are 2.08,438.14 and 1 348.05 mg/kg,much higher than the corresponding background values of soils in Chongqing city. The heavy metals concentrations in the surface sediment from Qingshui Stream are 0.84,189.75 and 838.23 mg/kg,and the values of index of geoaccumulation Igeo of Cd,Cu and Zn show that their pollution degrees are moderate. The heavy metals exist in three transferable forms such as water,suspended matter and surface sediment in Qingshui Stream. The heavy metals concentrations in water are the lowest,and those in the suspended matter are the highest,so the ecological risk in suspended matter is the highest. The distribution tendencies of three metals in water,suspended matter and surface sediment in main riverbed are different.展开更多
特高压(ultra high voltage,UHV)双柱悬索拉线塔风灾风险评估是实现其性能化抗风设计的重要组成部分,基于此,提出一种适用于特高压双柱悬索拉线塔的风灾风险评估方法。首先,建立特高压双柱悬索拉线塔风灾风险评估的基本框架;随后,基于...特高压(ultra high voltage,UHV)双柱悬索拉线塔风灾风险评估是实现其性能化抗风设计的重要组成部分,基于此,提出一种适用于特高压双柱悬索拉线塔的风灾风险评估方法。首先,建立特高压双柱悬索拉线塔风灾风险评估的基本框架;随后,基于该框架开展了新疆哈密地区的风灾危险性分析,并进行特高压双柱悬索拉线塔的风灾易损性分析;最后,利用所求得的风灾危险性函数和易损性函数卷积得到结构的风灾风险函数,计算得到结构在不同性能水准下的年失效概率,并讨论风向对结构风灾风险的影响。结果表明:新疆哈密地区NE风向方位所对应的风灾危险性最大,而S风向方位对应的风灾危险性则最小,应重点关注NE方位下的结构损伤;当风速小于44 m/s时,双柱悬索拉线塔在任意风向角下发生轻微破坏的概率都很小,结构具有较强的抗风性能;双柱悬索拉线塔在NE-90°工况组合和NE-0°工况组合下的年失效概率分别为最大和最小,其变化趋势与结构风灾易损性曲线相似;不同风向组合下双柱悬索拉线塔的年失效概率都很小,结构发生风致损伤及破坏为一小概率事件。展开更多
基金Project(KLVF-2007-4) supported by Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment,Ministry of Education,Chongqing University,ChinaProject(CSTC2008CE9095) supported by Chongqing Science and Technology Commission,ChinaProject(KJ080803) supported by Chongqing Municipal Education Commission,China
文摘Based on a detailed environmental investigation of the whole Qingshui Stream catchments,samples of water and surface sediments were collected at 15 different places from the upper to the lower reaches of Qingshui Stream,and samples of suspended matter were obtained by filtrating the water samples. The concentrations of heavy metals (Cd,Cu and Zn) were measured in filtered water,suspended matter,and surface sediment by ICP-AES. The results show that the concentrations of the three heavy metals in filtered water are 0.18,6.6 and 17.67 μg/L,lower than that of the Fresh Water Quality Criteria (US EPA) and those of the plain urban rivers,but the contents of Cd,Cu and Zn are much higher than the mean values of rivers in the world and the background value in Jialing River basin. The heavy metals concentrations in the suspended matter from Qingshui Stream are 2.08,438.14 and 1 348.05 mg/kg,much higher than the corresponding background values of soils in Chongqing city. The heavy metals concentrations in the surface sediment from Qingshui Stream are 0.84,189.75 and 838.23 mg/kg,and the values of index of geoaccumulation Igeo of Cd,Cu and Zn show that their pollution degrees are moderate. The heavy metals exist in three transferable forms such as water,suspended matter and surface sediment in Qingshui Stream. The heavy metals concentrations in water are the lowest,and those in the suspended matter are the highest,so the ecological risk in suspended matter is the highest. The distribution tendencies of three metals in water,suspended matter and surface sediment in main riverbed are different.
文摘特高压(ultra high voltage,UHV)双柱悬索拉线塔风灾风险评估是实现其性能化抗风设计的重要组成部分,基于此,提出一种适用于特高压双柱悬索拉线塔的风灾风险评估方法。首先,建立特高压双柱悬索拉线塔风灾风险评估的基本框架;随后,基于该框架开展了新疆哈密地区的风灾危险性分析,并进行特高压双柱悬索拉线塔的风灾易损性分析;最后,利用所求得的风灾危险性函数和易损性函数卷积得到结构的风灾风险函数,计算得到结构在不同性能水准下的年失效概率,并讨论风向对结构风灾风险的影响。结果表明:新疆哈密地区NE风向方位所对应的风灾危险性最大,而S风向方位对应的风灾危险性则最小,应重点关注NE方位下的结构损伤;当风速小于44 m/s时,双柱悬索拉线塔在任意风向角下发生轻微破坏的概率都很小,结构具有较强的抗风性能;双柱悬索拉线塔在NE-90°工况组合和NE-0°工况组合下的年失效概率分别为最大和最小,其变化趋势与结构风灾易损性曲线相似;不同风向组合下双柱悬索拉线塔的年失效概率都很小,结构发生风致损伤及破坏为一小概率事件。
