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31.
Integrated analysis of a coupled mechanism for the failure processes of pile-reinforced slopes 总被引:3,自引:1,他引:2
A series of centrifuge model tests was conducted to investigate the failure mechanism of pile-reinforced slopes under self-weight loading and vertical loading conditions. An integrated analysis method was proposed based on the image-based measurement results of the displacement of the slope in the tests. The failure process of a pile-reinforced slope was quantified based on the measured deformation process over the entire slope, which was shown to depend primarily on the loading conditions. The deformation localisation was discovered in the slope during loading and was effectively described using a newly introduced index, the Diversity Factor of Displacement (DFD). The deformation localisation of the slope developed and caused the progressive formation of the slip surface. At the same time, a local failure at a point on the slip surface resulted in new deformation localisation, and the influence expanded with the centre of the failure point and waned with increasing distance from the failure point. The deformation localisation process and the deformation-failure process of the piles interacted as both cause and effect and developed alternately. The failure mechanism of the pile-reinforced slopes was used to explain the effects of several influencing factors on the bearing capacity of the reinforced slope, such as the pile spacing, pile location, and gradient of the slope. 相似文献
32.
以内蒙古自治区西部阿拉善盟额济纳旗大狐狸山地区1:5万矿产远景调查为例,论述了遥感技术在1:5万矿产远景调查中的应用和具体工作方法。研究结果表明,在1:5万矿产远景调查中充分利用遥感技术,进行线性构造、环形构造、地质体的信息提取,利用主成分分析法有效提取矿化蚀变信息,在RGMAP数字平台,将工作区的标准影像图与其它数据源进行叠加整合,多轮回遥感地质解译成图,结合地质、物探、化探工作成果,快速有效地指导了地面找矿工作,对合理圈定找矿预测靶区起到了重要作用。 相似文献
33.
13C NMR spectroscopy was applied in the investigation of the structure of the organic matter in oil shales. By using Proton Enhanced Nuclear Induction Spectroscopy, a fair resolution of aliphatic and aromatic carbon signals was achieved. This method provided information on the relative ratio of aliphatic and aromatic carbons within a given set of samples (Aleksinac, Kimmeridge, Colorado, Australian torbanite and Estonian kukersite). 相似文献
34.
Proterozoic tectonic evolution and late Svecokarelian plate deformation of the Central Baltic Shield
Prof. Dr. Gabor Gaál 《International Journal of Earth Sciences》1982,71(1):158-170
The continental crust of the Central Baltic Shield evolved by accretion towards the west during the Svecokarelian orogeny 1700–2200 Ma ago. The following features are consistent with a plate tectonic mechanism involving subduction of oceanic crust below an Archean craton in the east: flysch-sediments with serpentinite masses and pillow lavas, linear high-grade metamorphic zones, island-arc type volcanic belts and late tectonic batholiths with porphyry type Cu-Mo deposits.Semi-consolidated new crust was affected by late Svecokarelian deformation (Dn) after 1850 Ma; NNE-trending folds with crenulation cleavage were overprinted on older structures together with associated NW trending ductile transcurrent shear zones that curve the Fn folds into gentle S and Z shapes. The late tectonic batholiths intruded partly at the same time as and partly after the Dn deformation.
Zusammenfassung Die kontinentale Kruste des zentralen Baltischen Schildes entwickelte sich durch nach Westen gerichtetes Anwachsen während der Svecokarelischen Orogenese vor 1700 bis 2200 Ma. Die folgenden Erscheinungsformen lassen sich mit einem plattentektonischen Mechanismus in Einklang bringen, der Subduktion von ozeanischer Kruste unter einen Archaischen Kraton im Osten einschließt: Flysch-Sedimente mit Serpentinit-Massen und Kissenlaven, lineare hochmetamorphe Zonen, vulkanische Gürtel vom Inselbogen-Typ und spättektonische Batholithe mit porphyrischen Cu-Mo-Lagerstätten.Die halbkonsolidierte neue Kruste wurde durch späte Svecokarelische Deformation (Dn) nach 1850 Ma erfaßt; NNE-orientierte Falten mit Krenulationsschieferung wurden älteren Strukturen aufgeprägt in Verbindung mit NW-streichenden, plastischen Transcurrent-Scherzonen, die die Fn-Falten in sanfte S- und Z-Formen verbiegen. Die spättektonischen Batholithe intrudierten teils während, teils nach der Dn-Deformation.
Résumé La croûte continentale du Boucher baltique central a évolué par voie d'accrétion vers l'ouest durant l'orogénie svécocarélienne 1700–2200 Ma. Les événements suivants sont en accord avec un mécanisme de tectonique de plaques impliquant la subduction d'une croûte océanique sous un craton archéen à l'est: sédiments flyschoïdes avec masses de serpentinite et de laves en coussins, zones linéaires à haut degré de métamorphisme, ceintures volcaniques du type guirlande d'îles et batholithes tectoniques tardifs avec gisements porphyriques de type Cu-Mo.La nouvelle croûte à semi-consolidée fut affectée par une déformation svécocarélienne tardive (Dn) postérieure à 1850 Ma. Des plis de direction NNE avec clivage de crénulation ont été superposés sur des structures plus anciennes, associés à des zones de cisaillement transcurrentes de direction NW qui ont incurvé les plis Fn suivant des formes en S et Z. Le batholithe tectonique tardif s'est mis en place en partie au même moment que, et en partie après, la déformation Dn.
, , 1500–2200 . , , : ; ; - . , 1850 ; NNE- , , NW , , Fn S Z. , .相似文献
35.
Miroslav Gačić Vedrana Kovačević Simone Cosoli Andrea Mazzoldi Jeffrey D. Paduan Isaac Mancero-Mosquera Sadegh Yari 《Estuarine, Coastal and Shelf Science》2009
Surface patterns of the low-frequency current in a 20 × 30 km region in front of the Venice Lagoon were analysed from a 13-month-long HF radar data set. Surface circulation was related to prevalent wind regimes in the area and to the tidal flow through the lagoon inlet. Three different categories of wind-forcing were defined: bora (NE wind), sirocco (SE wind), and finally the category containing all other wind directions and calms (winds lower than 3 m/sec). Mean flow and vorticity spatial distributions were discussed for different wind conditions. The coastal area about 5 km wide is characterized by a flow field with maximum vorticity. Outside the coastal boundary layer the interior flow is part of the Adriatic basin-wide cyclonic circulation. Two counter-rotating vortices of the dimension of about 4–5 km were evidenced in the average flow field in front of the lagoon inlet (Malamocco inlet) in all situations except for the bora. The vortex-pair is probably associated with the tidal flow through the inlet. The bora wind induces a strong southward coastal jet detached from the coast by about 5 km homogenizing the flow and eliminating the dipole. The average coastal flow pattern in calm wind conditions was also analysed as a function of the strong inflow/outflow (currents in the inlet > 0.7 m s−1) from the lagoon inlet. In both cases the vorticity pattern is similar, with the negative vorticity to the left of the inlet and positive to the right looking seaward. 相似文献
36.
37.
This study consisted in the characterization of internal waves in the south of the Strait of Messina (Italy). The observational data consisted in thermistor string profiles from the Coastal Ocean Acoustic Changes at High frequencies (COACH06) sea trial.An empirical orthogonal function analysis is applied to the data. The first two spatial empirical modes represent over 99% of the variability, and their corresponding time-dependent expansion coefficients take higher absolute values during internal wave events. In order to check how the expansion coefficients vary during an internal wave event, their time derivative, called here changing rates, are computed. It shows that each wave of an internal wave train is characterized by a double oscillation of the changing rates. At the front of the wave, both changing rates increase in absolute value with opposite sign, and then decrease to become null at the maximum amplitude of the wave. At the rear of the wave, the changing rates describe another period, again with opposite sign. This double oscillation can be used as a detector of internal waves, but it can also give information on the width of the wave, by measuring the length of the oscillation, as this information may sometimes be hard to read straight out of the data. When plotting the changing rates one versus another, the resulting scatter diagram puts on a butterfly shape that illustrates well this behaviour. 相似文献
38.
Gaëlle Serquet Christoph Marty Martine Rebetez 《Theoretical and Applied Climatology》2013,114(3-4):437-444
A better understanding of the impact of changing temperatures on snow amounts is very important for the ski industry, but it is difficult to measure, particularly at different times of the snow season and not only on an annual or seasonal basis. Here, we analyze the snow day vs precipitation day ratios on a monthly basis from November to April in Switzerland and at 52 meteorological stations located between 200 and 2,700 m above sea level over a 48-year time span. Our results show that the conditions measured in the 1960s in November and March correspond to the present ones in December, January, and February. 相似文献
39.
Dynamic loads, such as earthquakes, triggered a large number of landslides with more complicated failure mechanism due to their significant rate effect and cyclic effect. Thus, the failure mechanism is essential for an accurate evaluation of the dynamic stability of slopes. A series of centrifuge model tests was conducted to investigate the progressive failure behavior of slopes under cyclic loading conditions with different amplitudes. The cyclic effect was quantitatively analyzed in view of the deformation and failure behavior of slopes and was discovered equivalently induced by different combinations of the amplitude and the number of loading cycles. For example, the slope failure was induced by a cyclic loading with an increasing amplitude as the number of loading cycles decreased, with an extreme case of the monotonic loading with a larger magnitude. The slope exhibited a significant progressive failure with a downward sequence from the top. The slip surface became shallower as the amplitude of the cyclic loading increased and was shallowest under the monotonic loading condition. Cyclic loading induced deformation localization and the localization developed to cause local failure in the slope. The local failure, together with the effect of cyclic loading, contributed to new deformation localization that determined the development of the slip surface. The amplitude of the cyclic loading affected the propagation of deformation localization in slopes, resulting in the observed variation of the slip surfaces under different loading patterns. 相似文献
40.
Planning the Colca Canyon and the Valley of the Volcanoes National Park in South Peru 总被引:1,自引:1,他引:0
The economic development of the Rio Colca region and related infrastructure endangers the environment of the deepest canyon worldwide. The unique values of the Colca Valley and Canyon and its tributary Valley of the Volcanoes are summarised. They include a magnificent, deep section of the orogenic belt 100 km long, different geological formations, active faults, a variety of fold structures, young volcanoes, hot springs, geysers, several ecological zones and the largest condor habitat in the Andes. Based on the observed land use, development and regional planning, the threats and conflict areas are outlined. Studies performed by the Polish Scientific Expedition to Peru since 2003 add greatly to the knowledge of geology, landscape and pioneering biota development of the area and its importance to the world heritage of nature. They are aimed to give scientific background to the project of the Canyon Colca and Valley of the Volcanoes National Park. The article gives the proposed limits of the park and its buffer zones, categories of protection zones compatible with the SINANPE system of Peru and suggestions on tourist accessibility. The strict protection zone should cover the most inaccessible part of the area where human economic activity practically does not exist. Traditional farming and animal husbandry, wildlife, cultural tourism and some forms of adventure tourism will be allowed in the zone of special usage. The new park would strengthen the relatively poor system of the protected areas in the Arequipa Department, increase tourist attractiveness and determine constraints for sustained regional development. The expected actions of the park authority and local governments are specified. 相似文献