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1.
以某高速铁路线上一座连续梁桥为例,运用模糊综合评判法,结合基于位移的支座损伤分析和截面曲率的桥墩损伤分析,以全概率理论地震损失模型为基础,提出了基于模糊理论的桥梁系统地震经济风险评估方法。结果表明:综合考虑桥梁系统的模糊地震经济风险分析方法能更全面地计算出连续梁桥在地震作用下的经济损失,仅以桥墩构件代表全桥所得地震经济损失误差较大。基于模糊理论的年预期损失风险框架方法通过结构抗震性能的概率特征可对高速铁路连续梁桥的地震直接经济风险进行全面评估,为该类桥梁的抗震设计、维修加固和灾后重建等方案做出合理评价。  相似文献   
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Scientific and effective heritage monitoring can not only realize the conservation of the heritage itself and the maintenance of its values, but it can also realize the sustainable development of the heritage site. In order to promote the conservation and management of Globally Important Agricultural Heritage Systems (GIAHS), this study proposed a design for the annual report of GIAHS monitoring under the overall framework of the GIAHS monitoring system, and explored the application of the annual report in the first GIAHS site in China: the Qingtian Rice-Fish Culture System. In the design scheme of this study, the GIAHS annual monitoring report is composed of 24 monitoring items, with each of them logically related. It is to be filled in by the bureaus of the heritage site and reported through the GIAHS dynamic monitoring system. The results of an analysis of the annual reports of Qingtian Rice-Fish Culture System for four years showed that Qingtian County has taken a series of conservation and development measures which have reduced the area of abandoned paddy, enhanced the unit benefit of agri-products, and increased the farmers’ income. At the same time, the heritage site is faced with various challenges and threats, such as the weakening of the tourism attraction, the aging of the heritage practitioners, and the limitation of the heritage-themed agri-products and tourism income, which need to be addressed with proper measures. The results can also provide guidance for other GIAHS based on indications that heritage sites should improve the development of cultural products, the construction of social organization and the cultivation of spontaneous publicity, and an exchange and learning mechanism should be established among them in the future. The design and application of the GIAHS annual monitoring reports can not only provide specific guidance for conducting the GIAHS monitoring, but also lay the foundation for evaluating the effectiveness of GIAHS conservation and management. This study is expected to help enrich the theory of GIAHS monitoring, further promote China’s GIAHS monitoring work, and also provide China’s experience for the benefit of international GIAHS monitoring efforts.  相似文献   
4.
Few long-term studies have explored how intensively managed short rotation forest plantations interact with climate variability. We examine how prolonged severe drought and forest operations affect runoff in 11 experimental catchments on private corporate forest land near Nacimiento in south central Chile over the period 2008–2019. The catchments (7.7–414 ha) contain forest plantations of exotic fast-growing species (Pinus radiata, Eucalyptus spp.) at various stages of growth in a Mediterranean climate (mean long-term annual rainfall = 1381 mm). Since 2010, a drought, unprecedented in recent history, has reduced rainfall at Nacimiento by 20%, relative to the long-term mean. Pre-drought runoff ratios were <0.2 under 8-year-old Eucalyptus; >0.4 under 21-year-old Radiata pine and >0.8 where herbicide treatments had controlled vegetation for 2 years in 38% of the catchment area. Early in the study period, clearcutting of Radiata pine (85%–95% of catchment area) increased streamflow by 150 mm as compared with the year before harvest, while clearcutting and partial cuts of Eucalyptus did not increase streamflow. During 2008–2019, the combination of emerging drought and forestry treatments (replanting with Eucalyptus after clearcutting of Radiata pine and Eucalyptus) reduced streamflow by 400–500 mm, and regeneration of previously herbicide-treated vegetation combined with growth of Eucalyptus plantations reduced streamflow by 1125 mm (87% of mean annual precipitation 2010–2019). These results from one of the most comprehensive forest catchment studies in the world on private industrial forest land indicate that multiple decades of forest management have reduced deep soil moisture reservoirs. This effect has been exacerbated by drought and conversion from Radiata pine to Eucalyptus, apparently largely eliminating subsurface supply to streamflow. The findings reveal tradeoffs between wood production and water supply, provide lessons for adapting forest management to the projected future drier climate in Chile, and underscore the need for continued experimental work in managed forest plantations.  相似文献   
5.
利用青海省黄南地区近54a(1960—2013年)蒸发量、气温、降水量、日照时数、水汽压等资料,应用地理信息系统、数理统计、线性回归和Mann-Kendall检验等方法分析了黄南地区蒸发量的空间及时间变化趋势,并对黄南地区蒸发量变化特征及其影响因子进行了诊断研究。结果表明:黄南地区年平均蒸发量呈明显的下降趋势,20世纪60—70年代为蒸发量偏多阶段,80年代及后为偏少阶段;黄南地区蒸发量最大的季节是春季和夏季,各季蒸发量均呈减少趋势;黄南地区年蒸发量在1973年发生了由多到少的突变,春、夏、秋、冬季分别发在1973、1975、1976和1974年;分析影响蒸发量的相关因子,蒸发量与日照时数呈显著的正相关关系,与水汽压和降水量呈显著的负相关关系,日照时数的减小是蒸发量减少的主要影响因子。  相似文献   
6.
ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project (AMIP) results, we investigated annual and seasonal variation biases in the upper 50 m of the south-central equatorial Pacific, with a focus on the double-ITCZ bias, and examined the causes for the amplitude biases by using heat budget analysis. The results showed that, in the research region, most of the models simulate SSTs that are higher than or similar to observed. The simulated seasonal phase is close to that observed, but the amplitudes of more than half of the model results are larger than or equal to observations. Heat budget analysis demonstrated that strong shortwave radiation in individual atmospheric models is the main factor that leads to high SST values and that weak southward cold advection is an important mechanism for maintaining a high SST. For seasonal circulation, large surface shortwave radiation amplitudes cause large SST amplitudes.  相似文献   
7.
海原断裂带中东段地貌差异及其成因探讨   总被引:2,自引:1,他引:1       下载免费PDF全文
陈涛  张会平  王伟涛 《地震地质》2014,36(2):449-463
以定量化地形因子为切入点的构造地貌学方法已成为活动构造研究的有效手段,被广泛用于定性或半定量解析地貌对新构造运动的响应及其演化过程。针对海原断裂带中东段现今地貌差异,以SRTM 90m分辨率DEM为基础,利用ArcGIS软件和Matlab程序脚本,提取了海原断裂带中东段高程、坡度、地形起伏、地形侵蚀以及河流陡峭系数等地形因子。从空间分布上看,上述各项地形因子沿断裂走向均呈现 “西高东低”的整体分布特征。西段海拔高、坡度陡、起伏大、侵蚀强、抬升快,中段和东段海拔低、坡度缓、起伏小、侵蚀弱、抬升慢,此外,在断裂带的东南尾端呈略微增加趋势,达到小范围内的峰值。在此基础上,通过对比分析地形因子与年降水量、基岩岩性,初步探讨了构造与降水、岩性等因素对地形地貌的控制作用,认为不同降水条件对地貌后期改造起显著作用,基岩岩性与现今地貌之间并无显著关系,该区域地貌类型主要受构造抬升差异所控制。沿断裂带走向上的现今地貌差异表明,西段处于相对快速的构造隆升和强挤压造山构造背景,中段由于受到黄河下切及河流冲积作用影响,地貌参数记录的抬升特征并不显著,而东段则反映出大型断裂带尾端挤压调整效应。  相似文献   
8.
In order to analyze 3-dimensional movement and deformation characteristics and seismic risk of the Xianshuihe fault zone, we inverted for dynamic fault locking and slip deficit rate of the fault using the GPS horizontal velocity field of 1999-2007 and 2013-2017 in Sichuan-Yunnan region, and calculated annual vertical change rate to analyze the vertical deformation characteristics of the fault using the cross-fault leveling data during 1980-2017 locating on the Xianshuihe fault. The GPS inversion results indicate that in 1999-2007, the southeastern segment of the fault is tightly locked, the middle segment is less locked, and the northwestern segment is basically in creeping state. In 2013-2017, the southeastern segment of the fault is obviously weekly locked, in which only a patch between Daofu-Bamei is locked, and the northwestern segment is still mostly in creeping state, in which only a patch at southeastern Luhuo is slightly locked from surface to 10km depth. The cross-fault leveling data show that annual vertical change rate of the Zhuwo, Gelou, Xuxu and Goupu sites on the northwestern segment is larger, which means vertical movement is relatively active, and annual vertical change rate of the Longdengba, Laoqianning, and Zheduotang sites on the southeastern segment is small, which means the fault is locked, and the vertical movement changes little before and after the Wenchuan earthquake. Combining with the 3-dimensional movement and deformation, seismic activity and Coulomb stress on the Xianshuihe Fault, we consider the seismic risk of the southeastern segment is larger, and the Wenchuan earthquake reduced the far-field sinistral movement and the fault slip deficit rate, which may reduce the stress and strain accumulation rate and relieve the seismic risk of the southeastern segment.  相似文献   
9.
为了解象山近岸海域水质污染状况,文章根据2012—2016年象山县近岸海域的水质监测结果,分析象山近岸海域水质现状及年际变化。应用灰色预测的模型来对象山近岸海域水质主要污染物的相关数据进行处理,得出主要污染物的预测结果。分析结果表明:象山近岸海域主要污染物为无机氮。用预测结果和实际数值通过残差验证,最后模拟出今后几年的监测值,为象山县近岸海域生态环境相关管理部门提供数据支撑和决策依据。  相似文献   
10.
The conventional liquefaction potential assessment methods (also known as simplified methods) profoundly rely on empirical correlations based on observations from case histories. A probabilistic framework is developed to incorporate uncertainties in the earthquake ground motion prediction, the cyclic resistance prediction, and the cyclic demand prediction. The results of a probabilistic seismic hazard assessment, site response analyses, and liquefaction potential analyses are convolved to derive a relationship for the annual probability and return period of liquefaction. The random field spatial model is employed to quantify the spatial uncertainty associated with the in-situ measurements of geotechnical material.  相似文献   
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