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81.
介绍了在安徽膨胀土地区路基施工中,由于膨胀土存在压实困难、裂隙发育、易风化、吸水膨胀降低强度等缺陷,为解决填料短缺,降低工程造价,提高路基强度和整体稳定性,采用在膨胀土中掺石灰,改善膨胀土的结构,达到提高路基填筑质量的目的。 相似文献
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文章通过青海诺木洪—格尔木高速公路盐渍土路段勘察实例,指出了公路盐渍土勘察中应注意的事项,分析了高原盐渍土的成因,提出了盐渍土的重要物理力学指标、盐渍土路基的处理方法等。为西部高速公路勘察与设计提供了新的思路和方法,并对高原盐渍土勘察提供了范例。 相似文献
84.
Influences of local factors on permafrost occurrence and their implications for Qinghai-Xizang Railway design 总被引:6,自引:0,他引:6
CHENG Guodong State Key Laboratory of Frozen Soil Engineering Cold Arid Regions Environmental Engineering Research Institute Chinese 《中国科学D辑(英文版)》2004,47(8):704-709
Permafrost is a product of long-term energy ex-change between the atmosphere and the ground. Macro-scale distribution of permafrost is controlled overall by climate. However, site-specific variables such as terrain conditions, snow cover, soil/rock type, and moisture content can significantly modify the ef-fect of climate, resulting in localized anomalies in permafrost distribution[1,2]. These factors cause distur-bances to normal thermal regimes and can determine the presence and absence of p… 相似文献
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A one-dimensional, time-dependent cloud model with parameterized microphysics is used to investigate the processes which control the rainout and washout of soluble gases from warm, precipitating stratiform clouds. Calculations are presented simulating the distributions of soluble species within and below the cloud layer and in the precipitating raindrops as a function of time and species' solubility. Our calculations indicate that for species with low solubility, wet removal processes are relatively slow and thus do not significantly affect the species' gas-phase abundance. As a result, the removal of low-solubility species by rainout and washout is controlled by thermodynamic processes with the concentration of the species in cloud and rainwater largely determined by the species' solubility. For highly soluble species on the other hand, dissolution into cloud droplets and removal in rain is quite rapid and the abundance of highly soluble species within and below the cloud falls rapidly as soon as the precipitation begins. Because of this rapid decrease in concentration, we find that for highly soluble species: concentrations in cloud droplets near the cloud base can exceed that of raindrops by factors of 2 to 10; washout can dominate over rainout as a removal mechanism; and that, after an extended period of rainfall, the rate of removal becomes independent of the microphysical properties and rainfall rate of the cloud and is controlled by the rate of transport of material into the precipitating column by horizontal advection. 相似文献
87.
Theoretical models that describe the uptake of trace gases by water drops falling at terminal velocity in air have been extended to include the effects of aqueous phase chemical processes that occur on time scales comparable with or greater than that over which the relevant physical scavenging processes operate. In particular, the case of reversible dervative formation by the absorbed species has been treated, and illustrated by application to the absorption of acetaldehyde under conditions prevailing in the atmosphere. In addition, the relative influences of aqueous phase chemistry and of convective-diffusion on the efficiency of the scavenging process have been explored more generally, using the revised models. A brief comparison of the factors controlling the uptake of sulfur dioxide, dichloromethane, and acetaldehyde is presented. 相似文献
88.
保德矿区太原组桥头砂岩沉积特征与煤聚集 总被引:4,自引:1,他引:4
根据太原组桥头砂岩(体)的沉积特征(岩性、结构、沉积构造、古流特征、平面一剖面及三维空间上的几何形态)以及该砂体对下伏m13厚煤层的冲刷样式和对上覆m11煤聚集的独特控制方式,认为它属一种特殊过渡类型的河流环境的产物,并进一步分析了同沉积期的古构造背景。 相似文献
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