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31.
岩体结构面粗糙度系数JRC的定向统计研究 总被引:5,自引:2,他引:5
本文回顾了岩体结构面粗糙度系数JRC的研究成果,分析了各种JRC研究方法的应用范围。在野外实际结构面形态的详细调查和深入研究的基础上,发展了Barton直边法,并提出按岩性定向统计研究结构面粗糙度系数JRC的科学思想。 相似文献
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利用云、贵、川三省主要山系哀牢山、大娄山、大巴山的25个山地剖面气候站点,自1987-21-1990.2-28,19个气象要素的逐日观测资料,首次建立了西南三省山地剖面气象资料管理服务系统。系统具有资料管理、气候统计分析、资料比较等功能,适于科研、气候资料业务管理应用. 相似文献
33.
D. Murcray A. Goldman J. Kosters R. Zander W. Evans N. Louisnard C. Alamichel M. Bangham S. Pollitt B. Carli B. Dinelli S. Piccioli A. Volboni W. Traub K. Chance 《Journal of Atmospheric Chemistry》1990,10(2):159-179
The Balloon Intercomparison Campaign (BIC) was set up to intercompare remote sensing measurements of a number of compounds other than water vapor; however, water vapor has strong absorption features throughout the infrared and mm wave regions of the spectrum. Therefore many of the investigators involved in BIC have absorption or emission features due to water vapor in the data they obtained during the balloon flights made under the campaign. These features have been used by the investigators to determine the stratospheric water vapor profiles which are compared in this paper. The profiles allow comparison of a wide range of remote sensing techniques involving both emission and absorption in the mid-infrared and emission techniques in the far infrared. 相似文献
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This study attempts to reconstruct the history of the Collinabos landslide, a landslide with a fresh morphology that is representative for more than 150 dormant, deep-seated (> 3 m) landslides in the Flemish Ardennes (Belgium). A geomorphological map was created based on LIDAR (Light Detection and Ranging)-derived maps and detailed field surveys. The map showed that the landslide consisted of three zones with significant differences in surface topography. The northern landslide zone 1 is characterised by at least five reverse slopes, whereas zones 2 and 3, the southern landslide zones, have only two reverse slopes and a convex foot. Electric resistivity profiles measured in zones 1 and 2 revealed that the differences in surface topography were not related to differences in internal structure as both parts of the landslide were initiated as a rotational earth slide with a surface of rupture at 15 m deep, where the displaced material broke apart in two blocks. However, two shear surfaces of reactivations within landslide debris were only distinguished in the accumulation area of zone 1. The observed differences in surface morphology can be caused by a temporary conversion of a forest into cropland in zone 2. It is suggested that reverse slopes of smaller reactivations within landslide debris were obliterated during the agricultural activities. AMS radiocarbon dating of organic material found in ponds located in reverse slopes generally resulted in relatively recent dates (i.e. 1400–1950 Cal AD) suggesting that several of the small local reactivations occurred in that period. One dating at 8700–8440 Cal BP of organic matter collected in a reverse slope in zone 1 suggests that an initiation under periglacial conditions cannot be excluded for the Collinabos landslide. By combining different technologies, this study provides valuable information for a better understanding of dormant landslides. 相似文献
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Natural underground coal fires are fires in coal seams occurring subsurface. The fires are ignited through a process named spontaneous combustion, which occurs based on a natural reaction but is usually triggered through human interaction. Coal mining activities expose coal to the air. This leads to the exothermal oxidation of the carbon in the coal with the air's oxygen to CO2 and – under certain circumstances – to spontaneous combustion. Coal fires occur in many countries world wide – however, currently the Chinese coal mining industry faces the biggest problems with coal fires. Coal fires destroy the valuable resource coal and furthermore lead to many environmental degradation phenomena such as the deterioration of surrounding vegetation, land subsidence and the emission of toxic gasses (CO, N2O). They additionally contribute to the emission of green house relevant gasses such as CO2 and CH4 to the atmosphere.In this paper we present thermal characteristics of coal fires as measured in-situ during a field campaign to the Wuda coal fire area in south-central Inner Mongolia, China. Thermal characteristics include temperature anomaly measurements at the surface, spatial surface temperature profiles of fire areas and unaffected background areas, diurnal temperature profiles, and temperature measurements inside of coal fire induced cracks in the overlying bedrock. For all the measurements the effects of uneven solar heating through influences of slope and aspect are considered.Our findings show that coal fires result in strong or subtle thermal surface anomalies. Especially the latter can easily be influenced by heating of the surrounding background material through solar influences. Temperature variation of background rocks with different albedo, slope, aspect or vegetation cover can substantially influence the detectability of thermal anomalies. In the worst case coal fire related thermal anomalies can be completely masked by solar patterns during the daytime. Thus, night-time analysis is the most suitable for thermal anomaly mapping of underground coal fires, although this is not always feasible. The heat of underground coal fires only progresses very slowly through conduction in the rock material. Anomalies of coal fires completely covered by solid unfractured bedrock are very weak and were only measured during the night. The thermal pattern of underground coal fires manifested on the surface during the daytime is thus the pattern of cracks and vents, which occur due to the volume loss underground and which support radiation and convective energy transport of hot gasses. Inside coal fire temperatures can hardly be measured and can only be recorded if the glowing coal is exposed through a wider crack in the overlaying bedrock. Direct coal fire temperatures measured ranged between 233 °C and 854 °C. The results presented can substantially support the planning of thermal mapping campaigns, analyses of coal fire thermal anomalies in remotely sensed data, and can provide initial and boundary conditions for coal fire related numerical modeling.In a second paper named “Thermal Characteristics of Coal Fires 2: results of measurements on simulated coal fires” [Zhang J., Kuenzer C., Tetzlaff A., Oettl D., Zhukov B., Wagner W., 2007. Thermal Characteristics of Coal Fires 2: Result of measurements on simulated coal fires. Accepted for publication at Journal of Applied Geophysics. doi:10.1016/j.jappgeo.2007.08.003] we report about thermal characteristics of simulated coal fires simulated under simplified conditions. The simulated set up allowed us to measure even more parameters under undisturbed conditions — especially inside fire temperatures. Furthermore we could demonstrate the differences between open surface coal fires and covered underground coal fires. Thermal signals of coal fires in near range thermal remotely sensed imagery from an observing tower and from an airplane are presented and discussed. 相似文献
38.
R. Werner K. Stebel G.H. Hansen U. Blum U.-P. Hoppe M. Gausa K.-H. Fricke 《Journal of Atmospheric and Solar》2007,69(17-18):2249
During the last two decades, important advances have been made in the investigation of gravity waves. However, more efforts are needed to study certain aspects of gravity waves. In the real atmosphere, gravity waves occur with different properties at different altitudes and, most often, simultaneously. In this case, when there is more than one dominant wave, the determination of gravity wave characteristics, such as the vertical wavelength and the phase velocity, is difficult. The interpretation of temperature perturbation plots versus the altitude and time as well as the application of the Fourier spectral analysis can produce errors.Exact knowledge of the wave characteristics is important both for determination of other characteristics, for example, the horizontal wave components, and for study of wave climatology. The wavelet analysis of vertical temperature profiles allows one to examine the wave's location in space. Up to now, gravity waves have been studied mainly by continuous wavelet transformation to determine dominant waves. We apply wavelet analysis to a time series of temperature profiles, observed by the ALOMAR ozone lidar at Andoya, Norway, and by the U. Bonn lidar system at ESRANGE, Sweden, both for determination of the dominant waves and for specifying the vertical wavelengths and the vertical component of the phase velocities. For this purpose, the wavelet amplitude spectra and the wavelet phase spectra are filtered and Hovmöller diagrams for dominant wavelengths are constructed. The advantage of this type of diagrams is that they give clear evidence for the localization of the dominant waves in space and time and for the development of their phase fronts. 相似文献
39.
Saltmarsh vegetation significantly influences tidal currents and sediment deposition by decelerating the water velocity in the canopy. In order to complement previous field results, detailed profiles of velocity and turbulence were measured in a laboratory flume. Natural Spartina anglica plants were installed in a 3 m length test section in a straight, recirculating flume. Different vegetation densities, water depths and surface velocities were investigated. The logarithmic velocity profile, which existed in front of the vegetation, was altered gradually to a skimming-flow profile, typical for submerged saltmarsh vegetation. The flow reduction in the denser part of the canopy also induced an upward flow (the current was partially deflected by the canopy). The skimming flow was accompanied by a zone of high turbulence co-located with the strongest velocity gradient. This gradient moved upward and the turbulence increased with distance from the edge of the vegetation. Below the skimming flow, the velocity and the turbulence were low. The structure of the flow in the canopy was relatively stable 2 m into the vegetation. The roughness length (z0) of the vegetation depends only on the vegetation characteristics, and is not sensitive to the current velocity or the water depth. Both the reduced turbulence in the dense canopy and the high turbulence at the top of the canopy should increase sediment deposition. On the other hand, the high turbulence zone just beyond the vegetation edge and the oblique upward flow may produce reduced sedimentation; a phenomenon that was observed near the vegetation edge in the field. 相似文献
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