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以某铁路隧道检测为例,首先简单阐述高频地质雷达探测应用的原理,然后着重对隧道衬砌检测结果数据进行分析和研究,得到了隧道衬砌厚度和某些地段衬砌内存在空洞、充填不实等不良情况,为实际工程检测衬砌质量提供了科学依据。 相似文献
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简述地质雷达在隧洞衬砌质量检测中的原理及方法,结合工程实例将地质雷达与钻芯验证相结合,对隧洞衬砌厚度、钢筋分布检测结果进行对比分析,并将成果应用于多座水库隧洞衬砌的质量检测,结果表明:地质雷达对隧洞混凝土钢筋分布、混凝土厚度及衬砌情况探测效果较好。 相似文献
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简述采用地质雷达检测水利工程隧洞衬砌质量的原理及方法,结合某水电站引水发电洞实例,介绍了探地雷达探测剖面图的解读方法。实践证明:地质雷达对隧洞混凝土钢筋分布、混凝土厚度及衬砌质量探测效果较好。 相似文献
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地雷达即地质雷达(Ground Penetrating Radar(GPR))是一种利用高频电磁波技术探测地下物体的电子设备。随着时代的不断发展和社会的不断进步,地质雷达也在随着时代不断地发展,在现如今的地质雷达当中,做常做的工作便是进行隧道衬砌的质量检测,利用地质雷达进行隧道衬砌检测工作具有方便、快速、便捷等优点。但... 相似文献
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本文简要介绍了地质雷达检测水利工程隧洞质量的基本原理和方法,并结合实际,通过对新疆阜康白杨河水库导流洞混凝土衬砌检测的地质雷达图像进行分析,直观反映出隧道衬砌厚度、空洞及内部钢筋的分布等特征。结果表明,地质雷达检测技术能够直观地反应出工程隧洞内部结构,进而可以准确地查出混凝土结构内部缺陷的类型和位置,为后期修补提供技术支持。 相似文献
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利用地质雷达进行隧道超前预报和衬砌质量的检测是当下研究的一个重要的方向,而地质雷达正演模拟在隧道方面的应用,主要集中于隧道超前预报和隧道衬砌等方面。本文在研究地质雷达检测原理和正演模拟原理的基础之上,对地质雷达正演模拟在隧道衬砌检测方面的研究进行了概括,并总结出目前学者研究的不足之处。最后提出,地质雷达正演在隧道方面的研究,应更加致力于智能算法的引入、三维正演模拟、图像去噪、正演模拟软件的开发,这样才能更好的为隧道工程的检测提供帮助。 相似文献
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结合国内外地质雷达技术发展与应用,简述了基于引水隧道工作原理的隧道衬砌地质雷达检测技术,并得到地质雷达应用于浅埋深小断面引水隧道具有极其广阔的前景等结论。地质雷达技术可有效地对隧道混凝土的密实度、与岩体的接触紧密度等进行连续、全面、快速、精确的无损伤检测。 相似文献
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根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。 相似文献
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The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects. 相似文献
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Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river. 相似文献
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In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed
in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash
and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers
of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional
components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect
dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system,
configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants
of dry ash utilization and the advantages of producing of size-separated particles are considered.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed. 相似文献