日本琵琶湖表面定振波的计算

利用水动力学方程对口本琵琶湖表面定振波进行了计算和分析,结果表明其主要周期约为69．5min,另外,利用实测水位资料,采用最大熵谱法进行分析,得到了主要周期约为68min,两者吻合很好。     

CFRP加固一字形竖缝耗能预制剪力墙抗震性能研究

以一字形竖缝耗能预制剪力墙作为研究对象,设计了3个装配式剪力墙试件及1个现浇剪力墙对比试件,进行低周往复荷载试验,并对破坏墙体进行CFRP加固,再次进行拟静力试验。试件变化参数包括轴压比、混凝土强度等级及配筋率,对比分析加固前后试件滞回性能、刚度退化、承载力和耗能能力等性能。试验结果表明,与现浇剪力墙相比,一字形竖缝耗能预制剪力墙工作性能良好,阻尼器屈服耗能提高了试件整体工作性能;CFRP加固可有效抑制墙体斜裂缝的发展,对墙体承载力及耗能能力均有显著改善作用;各试件均满足剪力墙弹塑性层间位移角限值要求,延性较好;试件整体表现出良好的抗震性能。     

VOLUMETRIC SEDIMENT CONCENTRATION IN DEBRIS FLOWS

1　ＩＮＴＲＯＤＵＣＴＩＯＮ　Ｄｅｂｒｉｓｆｌｏｗｓｏｃｃｕｒｗｈｅｎｒａｉｎｓｔｏｒｍｓｏｒｔｈｅｅｌｅｖａｔｉｏｎｏｆｕｎｄｅｒｇｒｏｕｎｄｗａｔｅｒｌｅｖｅｌｃａｕｓｅｌｏｏｓｅｄｅｐｏｓｉｔｓｏｒｐｅｔｒｉｆｉｅｄｏｂｊｅｃｔｓｓｕｃｈａｓｐ?..     

Geochemistry and genesis of authigenic pyrite from gas hydrate accumulation system in the Qilian Mountain permafrost,Qinghai, northwest China

A type of authigenic pyrites that fully fill or semi-fill the rock fractures of drillholes with gas hydrate anomalies are found in the Qilian Mountain permafrost; this type of pyrite is known as “fracture-filling” pyrite. The occurrence of “fracture-filling” pyrite has a certain similarity with that of the hydrate found in this region, and the pyrite is generally concentrated in the lower part of the hydrate layer or the hydrate anomaly layer. The morphology, trace elements, rare earth elements, and sulfur isotope analyses of samples from drillhole DK-6 indicate that the “fracture-filling” pyrites are dominated by cubic ones mainly aligned in a step-like fashion along the surfaces of rock fractures and are associated with a circular structure, lower Co/Ni and Sr/Ba, lower ΣREE, higher LREE, significant Eu negative anomalies, and Δ³⁴S_CDT positive bias. In terms of the pyrites’ unique crystal morphology and geochemical characteristics and their relationship with the hydrate layers or abnormal layers, they are closely related with the accumulation system of the gas hydrate in the Qilian Mountain permafrost. As climate change is an important factor in affecting the stability of the gas hydrate, formation of fracture-filling pyrites is most likely closely related to the secondary change of the metastable gas hydrate under the regional climate warming. The distribution intensity of these pyrites indicates that when the gas hydrate stability zone (GHSZ) is narrowing, the hydrate decomposition at the bottom of the GHSZ is stronger than that at the top of the GHSZ, whereas the hydrate decomposition within the GHSZ is relatively weak. Thus, the zone between the shallowest and the deepest distribution of the fracture-filling pyrite recorded the largest possible original GHSZ.     

Mesozoic paleogeography and tectonic evolution of South China Sea and adjacent areas in the context of Tethyan and Paleo-Pacific interconnections

Abstract   During the Mesozoic era, the South China Sea and its environs were located at the south-eastern margin of the Eurasian continent. There has been hot debate on the influences of Tethyan and Paleo-Pacific tectonics to the Mesozoic evolution of the area. This paper compiles lithofacies maps of six time slices and discusses the paleogeographic and tectonic evolution of the area based on this compilation and other data on structural deformation and magmatism. In the Early Triassic, the Paleotethys Ocean extended eastward to the study area through the Song Da passage. Then a significant east–west differential evolution began. In the Late Triassic, the western area uplifted as a result of the collision between the Indosinian and South China blocks during the Indosinian orogeny, and the Song Da passage has closed since then. Meanwhile, a transgression of Paleo-Pacific waters occurred in the eastern and south-eastern portions of the area, forming the 'East Guangdong–North-west Borneo Sea'. In the Early Jurassic, seawater transgression was even more pronounced, resulting into the connection of this sea with the Mesotethys Ocean to the west. Large quantities of Tethyan water carrying Tethyan organisms entered the area. In the Middle Jurassic, a short-lived transgression occurred in the eastern Mesotethys and resulted in the formation of the 'Yunnan–Burma Sea'. The Late Jurassic to Early Cretaceous was the climax of the subduction of both the Mesotethys and Paleo-Pacific towards the Eurasian continent. This led to the formation of the great 'Circum South-east Asia Subduction–Accretion Zone' in the Middle or Late Cretaceous. This paper also presents various lines of evidence for a newly recognized segment of this Mesozoic subduction–accretion zone buried under Cenozoic sediments in the north-eastern South China Sea.     

The formation evaluation tool and its application in offshore China

The Formation Evaluation Tool （FET） introduced in the paper represents a new generation of formation evaluation systems developed and manufactured by China Oilfield Services Limited （COSL）, CNOOC, using a FET technology transfer from Crocker Research, Australia. The system has been applied successfully in the Bohai Sea and South China Sea. For instance, a multilayered oil and water system has been confirmed with the aid of accurate formation pressure tests, even in very thin beds and edge water reservoirs, overcoming the difficulty of determining this kind of oil-water and gas-water contacts. Moreover, the FET pumping and real-time fluid monitoring function allows acquiring a true sample of formation fluid unpolluted by drilling mud which plays an important role in determining the fluid properties of the target stratum and analyzing the fluid component. The principles and purpose of the Formation Evaluation Tool （FET） will be briefly introduced and successful examples of the application of the technology will be described in detail in this paper.     

基于手机位置数据的地震灾情指标选择

选取四川阿坝州九寨沟县MS7.0地震、新疆博尔塔拉州精河县MS6.6地震、四川广元市青川县MS5.4地震作为案例分析,绘制活跃Wi Fi数量、无线网络联网设备数量、汇总在线设备数量、活跃基站数量等4种地震灾情指标在地震发生前后数量变化的折线图。根据与地震前1天变化情况的对比分析,验证地震灾情指标的可用性,选取出效果好的指标,这对进一步研究震后快速获取极震区位置、影响场方向等具有重要意义。     

Preliminary results of the close-off depth and the stable isotopic records along a 109.91 m ice core from Dome A,Antarctica

A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other co...     

Groundwater recharge in an arid grassland as indicated by soil chloride profile and multiple tracers

Previous studies have shown that shallow groundwater in arid regions is often not in equilibrium with near‐surface boundary conditions due to human activities and climate change. This is especially the case where the unsaturated zone is thick and recharge rate is limited. Under this nonequilibrium condition, the unsaturated zone solute profile plays an important role in estimating recent diffuse recharge in arid environments. This paper combines evaluation of the thick unsaturated zone with the saturated zone to investigate the groundwater recharge of a grassland in the arid western Ordos Basin, NW China, using the soil chloride profiles and multiple tracers (²H, ¹⁸O, ¹³C, ¹⁴C, and water chemistry) of groundwater. Whereas conventional water balance and Darcy flux measurements usually involve large errors in recharge estimations for arid areas, chloride mass balance has been widely and generally successfully used. The results show that the present diffuse recharge beneath the grassland is 0.11–0.32 mm/year, based on the chloride mass balance of seven soil profiles. The chloride accumulation age is approximately 2,500 years at a depth of 13 m in the unsaturated zone. The average Cl content in soil moisture in the upper 13 m of the unsaturated zone ranges from 2,842 to 7,856 mg/L, whereas the shallow groundwater Cl content ranges from 95 to 351 mg/L. The corrected ¹⁴C age of shallow groundwater ranges from 4,327 to 29,708 years. Stable isotopes show that the shallow groundwater is unrelated to modern precipitation. The shallow groundwater was recharged during the cold and wet phases of the Late Pleistocene and Holocene humid phase based on palaeoclimate, and consequently, the groundwater resources are nonrenewable. Due to the limited recharge rate and thick unsaturated zone, the present shallow groundwater has not been in hydraulic equilibrium with near‐surface boundary conditions in the past 2,500 years.     

冬小麦农田裸温与气温差异分析及其应用

以矮秆代表作物冬小麦为研究对象,利用郑州农业气象试验站2010年10月15日—2011年6月2日农田小气候观测的各层裸温、气温、总辐射和覆盖度资料,采用对比差值、温度垂直梯度等方法统计分析,并对温度对比差值和总辐射曝辐量相关关系和温度的垂直梯度分布特征进行了研究,结果表明:25cm、150cm和300cm高度的日平均裸温和气温变化趋势基本一致,其对比差值呈由小变大趋势;各层裸温和气温的日分布符合温度日变化分布的一般规律,垂直梯度变化比较明显;各层对比差值呈单峰分布,峰值出现在正午12时左右;裸温和气温的对比差值与总辐射曝辐量呈线性相关。裸温与气温的垂直梯度变化有很好的一致性,可利用裸温不同层次间垂直梯度变化特征确定气温传感器合理的安装高度;根据麦田裸温垂直梯度变化特征,考虑到温度防辐射罩高度限制,矮秆作物田间小气候气温应在距离地表面25cm、50cm和150cm高度附近分别设置观测层次。