拱形波纹钢屋盖动力特性测试及分析   总被引：2，自引：0，他引：2  

王小平蒋沧如  胡春宇李桂青 《地震工程与工程振动》2005,25(5):112-116

拱形波纹钢屋盖是一种新颖的金属拱形薄壳结构，在我国已经得到了广泛的应用。由于结构的复杂性，目前有关的理论研究尚不够深入，动力研究还很少有人涉及。以18m和30m两种跨度的W666型拱形波纹钢屋盖为研究对象，测试了拱在竖向平面内振动时的频率、振型及阻尼。在所提简化计算模型的基础上，采用有限元方法计算了结构的动力特性，其结果与试验数据符合较好。测试和分析结果为该结构的动力反应研究提供了方便。  相似文献   

Physicochemical properties of fine aerosols at Plan d'Aups during ESCOMPTE     

Angela Marinoni  Paolo Laj  Pierre Alexandre Deveau  Federica Marino  Grazia Ghermandi  Fabien Aulagnier  Hlne Cachier 《Atmospheric Research》2005,74(1-4):565-580

The physical and chemical properties of aerosol particles were investigated at Plan d'Aups, one of the ESCOMPTE sites located in the St. Baume mountain area (700 m a.s.l.), 50 km east of Marseilles (France). The site is ideally located for assessing the vertical and horizontal extent of the pollution plume from the Marseilles–Berre area.Our study showed that polluted air masses from the Marseilles–Berre area are advected to Plan d'Aups in the early afternoon. Average daily concentration of particles reaches up to 40 μg m⁻³ while 1-h average particle number concentration is greater than 30,000 cm⁻³. Most of the particle mass is composed of SO₄²⁻ and organic carbon (OC). The chemical properties of the particles revealed that an additional source, possibly from the industrial area of Gardanne, contributes to the aerosol mass. This last source is characterised by significant emissions of elements, such as Zn, V, Al and Si.In addition to transport, we found that gas-to-particle conversion takes place at the interface between the free troposphere and the boundary layer. We estimated that on average, 30% of the particle number is accounted for by direct nucleation. This is potentially a major aerosol source to the free troposphere.  相似文献   

苏北榴辉岩的岩石性质及其金红石的嵌布特征   总被引：2，自引：1，他引：2  

张梅 《江苏地质》2005,29(2):82-87

苏北榴辉岩主要产于由角闪岩相变质的长英质片麻岩，根据其赋存部位划分为3类：Ⅰ类榴辉岩，通常形成独立块体，有时夹薄层片麻岩、片岩，岩石呈块状、条带状、斑杂状、条纹状和片麻状等；Ⅱ类榴辉岩，与超基性岩相伴，矿石主要呈块状和斑杂状；Ⅲ类榴辉岩，与大理岩整合接触，岩石呈块状、片麻状。3类榴辉岩在变晶矿物组合中具有一定的差异。面积测量法统计结果表明：Ⅰ类榴辉岩的晶间金红石占12．49%，间粒金红石占85．69％，包体金红石占1．81％；Ⅱ类榴辉岩的晶间金红石占36．40％，间粒金红石占44．17%，包体金红石占19．43％．Ⅲ类榴辉岩的晶间余红石占27．49％．间粒会红石占53．43%，包体金红石占19．09％。  相似文献   

豫西东部黄土工程特性研究     

王现国 《水文地质工程地质》2005,32(2):58-61

豫西东部堆积了第四纪不同时期的风成黄土及冲积、冲洪积黄土状土,全新统黄土、上更新统黄土具有湿陷性,为弱—中等湿陷。中更新统黄土一般不具有湿陷性。黄土的微观结构与土的形成时代、成因类型关系密切,全新统黄土颗粒间为开放或次开放式架空结构,具有较高的湿陷性,上更新统黄土接近接触式胶结,存在粒间架空孔隙,潜在弱—中等湿陷性;中更新统黄土为不等粒基底胶结结构,存在骨架接触式孔隙,一般不具有湿陷性;同时,黄土的渗透性又具有各向异性。  相似文献   

Mass movements in cave sediments: investigation of a ∼40,000-year-old guano mudflow inside the entrance of the Great Cave of Niah, Sarawak, Borneo     

A. P. Dykes 《Landslides》2007,4(3):279-290

The West Mouth of the Great Cave at Niah in Sarawak, northwest Borneo and the North Passage that leads to the West Mouth contain large deposits of guano. The main deposit, several metres thick in places, forms the sloping floor of the entire North Passage. A mass movement deposit identified in the West Mouth, having a volume of 600 m³, originated as a guano mudflow up the North Passage in the order of 40,000 years ago. This failure of the guano slope was investigated to determine whether particular conditions or events could be identified as the most likely causes. The physical, hydrological and geotechnical properties of samples of the material were determined so that the stability of the slope could be assessed. Stability analyses showed that shearing failure of the slope would require inputs of water to the slope in quantities for which no feasible explanation can be suggested. However, the properties of the guano are similar to those of loess, indicating a high susceptibility to ‘hydrocollapse’. Very shallow failure of the slope, possibly as several smaller mudflows, could therefore have occurred due to additional water in quantities that could realistically be supplied as rainwater spray, possibly with a seismic trigger. The climate must therefore have been wetter than it is at present. These findings have implications for the interpretation of sediment deposits in other relict caves.  相似文献   

Post-drilling destabilization of temperature profile in borehole Yaxcopoil-1, Mexico     

Jan Šafanda  Philipp Heidinger  Helmut Wilhelm  Vladimír Čermák 《Hydrogeology Journal》2007,15(2):423-428

As part of the International Continental Scientific Drilling Program (ICDP), the 1.5-km-deep borehole Yaxcopoil-1, located in the Chixculub meteor impact structure in Mexico, has undergone further study after drilling operations ceased. Temperature logs were repeated ten times at intervals 0.3–0.8, 15, 24 and 34 months after borehole shut-in. The logs bear a distinct signature of transient heat transfer by groundwater flow manifested by a gradual distortion of the linear temperature profile when a cold wave of 0.8–1.6°C amplitude was detected propagating downward from 145 to 312 m at a rate of 4–6 m/month. To understand the nature of this moving anomaly, a 20-day monitoring of the cold wave was carried out at a depth of 307 m that showed further cooling of 0.6°C during the first 16 days of the passage followed by temperature stabilisation. As an explanation of this unusual phenomenon, a theory is proposed, whereby the drilling mud has accumulated within the overlying and cooler highly porous and permeable karstic rocks during the drilling and migrates downward. The observed migration rate suggests a permeability higher than 10^?11 m². This indicates a high vulnerability to contamination of the only freshwater aquifer in the Yucatan region.  相似文献   

A case study to verify methods for estimating transmissivity distributions along boreholes     

Åsa Fransson 《Hydrogeology Journal》2007,15(2):307-313

Two methods, both using data from fixed-interval-length hydraulic tests and geological mapping on different scales, have been utilised to estimate transmissivity distributions of individual fractures. Individual fracture properties are of importance in estimating transport of water and solutes; they influence the spreading of grout when sealing tunnels. One of the methods is non-parametric, while the other is based on combinatorics and the multiplication principle. The study verified the usefulness of both methods for estimating the probability of conductive and non-conductive fractures, and the transmissivity distributions. Data for estimating transmissivity distributions originate from flow logging of a borehole in Sweden. Fracture frequency data are from core logging and images using a borehole image processing system (BIPS). Estimated transmissivity distributions, based on flow log data from 3-m sections (test scale length, L: 3 m, and step length, dL: 3 m), were compared with transmissivities obtained directly from detailed, overlapping flow logging which identify individual conductive fractures (test scale, L: 0.5 m, step length, dL: 0.1 m). The latter data are considered to be an acceptable approximation of the individual fracture transmissivities; the agreement, compared with the calculated transmissivity distributions based on 3-m section data, is good for both methods.

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Resumen Se han utilizado dos métodos, ambos procesando datos de pruebas hidráulicas de longitud e intervalo fijo y mapas geológicos en distintas escalas, para estimar las distribuciones de transmisividad de fracturas individuales. Las propiedades de fracturas individuales son de importancia para estimar el transporte de agua y solutos; las propiedades influyen en la propagación de lechada al sellar túneles. Uno de los métodos es no paramétrico mientras que el otro se basa en el principio de multiplicación y combinatorio. El estudio verifica la utilidad de ambos métodos para estimar la probabilidad de fracturas conductivas y no conductivas y las distribuciones de transmisividad. Los datos para estimar las distribuciones de transmisividad se originan del registro de flujo de un pozo en Suecia. Los datos de frecuencia de fracturas provienen de registros de núcleo e imágenes usando un Sistema de Procesamiento de Imágenes de Pozo (BIPS). Se compararon las distribuciones estimadas de transmisividad basadas en datos del registro de flujo en secciones de 3 m (longitud de escala de la prueba L: 3 m, y escalón de longitud dL: 3 m), con transmisividades obtenidas directamente de registros detallados de flujo superpuesto el cual identifica fracturas conductivas individuales (escala de la prueba, L: 0.5 m, escalón de longitud, dL: 0.1 m). Los últimos datos se consideran una aproximación aceptable de las transmisividades de fracturas individuales; la consistencia, comparada con las distribuciones de transmisividad calculada basadas en datos de sección de 3 m, es buena para ambos métodos.

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Résumé Deux méthodes ont été testées afin d’estimer la distribution des transmissivités de fractures unitaires; toutes deux utilisent des données issues de tests hydrauliques effectués à intervalles réguliers et de cartographies géologiques à plusieurs échelles. La connaissance des propriétés des fractures unitaires est importante pour estimer le transport d’eau et de solutés; elles influencent en outre l’étalement du coulis lors du scellement des tunnels. La première méthode est non-paramétrique, et la seconde repose sur l’analyse combinatoire et le principe de multiplication. Cette étude a vérifié l’utilité des deux méthodes pour estimer la probabilité d’occurrence de fractures conductrices et non-conductrices, et la distribution des transmissivités. Les distributions des transmissivités ont été estimées à partir de diagraphies effectuées sur un forage situé en Suède. Les densités de fracturation proviennent de carottages et d’imagerie BIPS (Borehole Image Processing System). Les distributions estimées des transmissivités, basées sur des diagraphies de flux effectuées sur des sections de 3 m (échelle du test L:3 m; pas dL:3 m), ont été comparées aux transmissivités obtenues sur des diagraphies de flux détaillées et se chevauchant, identifiant les fractures conductrices unitaires (échelle du test L: 0.5 m ; pas dL: 0.1 m). Il est admis que ces dernières données représentent une approximation satisfaisante des transmissivités des fractures unitaires; les deux méthodes sont en accord avec les distributions des transmissivités calculées à partir des données acquises sur des sections de 3 m.

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Hydraulic properties of the crystalline basement   总被引：1，自引：1，他引：1  

Ingrid Stober  Kurt Bucher 《Hydrogeology Journal》2007,15(2):213-224

Hydraulic tests in boreholes, up to 4.5 km deep, drilled into continental crystalline basement revealed hydraulic conductivity (K) values that range over nine log-units from 10⁻¹³−10⁻⁴ m s⁻¹. However, K values for fractured basement to about 1 km depth are typically restricted to the range from 10⁻⁸ to 10⁻⁶ m s⁻¹. New data from an extended injection test at the KTB research site (part of the Continental Deep Drilling Program in Germany) at 4 km depth provide K=5 10⁻⁸ m s⁻¹. The summarized K-data show a very strong dependence on lithology and on the local deformation history of a particular area. In highly fractured regions, granite tends to be more pervious than gneiss. The fracture porosity is generally saturated with Na–Cl or Ca–Na–Cl type waters with salinities ranging from <1 to >100 g L⁻¹. The basement permeability is well within the conditions for advective fluid and heat transport. Consequently, fluid pressure is hydrostatic and a Darcy flow mechanism is possible to a great depth. Topography-related hydraulic gradients in moderately conductive basement may result in characteristic advective flow rates of up to 100 L a⁻¹ m⁻² and lead to significant advective heat and solute transfer in the upper brittle crust. An erratum to this article can be found at  相似文献   

Performance Prediction of Circular Diamond Saws from Mechanical Rock Properties in Cutting Carbonate Rocks   总被引：2，自引：0，他引：2  

M. Fener  S. Kahraman  M. O. Ozder 《Rock Mechanics and Rock Engineering》2007,40(5):505-517

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腾格里沙漠东南缘白刺灌丛地土壤性状的特征   总被引：7，自引：0，他引：7  

贾晓红  李新荣  陈应武 《干旱区地理》2007,30(4):57-564

腾格里沙漠东南缘白刺灌丛地土壤颗粒组成中仍以细沙粒(0.25～0.05 mm)含量占主要成分(80%～99%),除固定沙堆土0～5 cm土壤粉沙粒含量高于堆间低地外,沙堆土不同深度粉沙粒含量(0.05～0.002 mm)均低于堆间低地;沙堆不同部位的土壤含水量有一致的变化趋势且差异不大,沙堆0～60 cm土层含水量低于堆间低地,60 cm以下的土壤含水量不仅高于0～60 cm,并且高于堆间低地。发育于草甸盐土上的堆间低地20 cm以下水分含量变化基本保持在较高的水平,发育于盐化半固定风沙土上的堆间低地水分含量在20 cm以下呈急剧降低趋势。白刺沙堆上土壤剖面土壤水分含量的这种变化和堆间低地20 cm处较高的含水层,将会为灌丛植物在年内气候干旱期的生命维持提供着重要水源保证。土壤容重白刺沙堆大于堆间低地,土壤剖面堆间低地的容重基本无变异,而沙堆上因为植物发育土壤容重有不同程度的差异。表征土壤肥力和保肥能力的阳离子代换量均是堆间低地大于沙堆上。堆间低地和沙堆上土壤全氮、有机质、电导率含量和pH值差异因白刺沙堆发育的生境不同而不同,处于半固定沙地生境的白刺沙堆并未形成灌丛的"沃岛效应",处于固定沙地生境的白刺沙堆有弱"沃岛效应"。因此,白刺沙堆地表物质的固定是该植物种生长的生境产生"沃岛效应"的前提。  相似文献