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论三维等时线叠加反偏移中的有关问题 总被引:6,自引:2,他引:6
孙建国 《吉林大学学报(地球科学版)》2002,32(3):273-278
利用几何射线理论和一种考虑了积分域边缘贡献的二维稳想法,研究了三维等时线叠加反偏移中的反偏移场,反偏移加权函及反偏移孔径。结果证明,在有限孔径条件下,反偏移场的结构比已发表的结果要复杂和多。即使在最简单的条件下,反偏移场也是由反偏移信号的反偏移噪声(孔径效应)叠加而成的。而且,反偏移场的结构强烈地依赖于反偏移孔径边缘的位置。为了消除孔径效应,应采用最佳反偏移孔径和针对有限孔径的加权函数。根据定义,最佳反偏移孔径为稳相点的第一和第二Fresnel区之和。在第一Fresnel区内,有限孔径和加权函数与文献中所给出的加权函数完全一致。而在第二Fresnel区内,有限孔径加权函数为常规的加权函数与一窗函数的乘积。在反偏移孔径的边缘上,有限孔径加权函恒取零值。 相似文献
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高密度电法勘探在岩溶查找中的应用 总被引:10,自引:0,他引:10
介绍了武汉市汤逊湖污水处理厂厂址的地质概况和地球物理特征,以及高密度电法勘探的施工方案,分析了视电阻率异常特征,并说明了其异常验证情况。高密度电法勘探结果表明该区存在溶洞,为施工提供了决策依据,建议在有溶洞的地段采取相应措施,以防止工程建设后发生地质灾害。 相似文献
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Structural and geotechnical impacts of surface rupture on highway structures during recent earthquakes in Turkey 总被引:4,自引:0,他引:4
The most significant damage on highway bridges during the recent earthquakes in Turkey (Kocaeli and Duzce earthquakes) and Taiwan (Chi–Chi earthquake) was the result of fault ruptures traversing transportation infrastructure. This phenomenon and its consequences accentuate the need to examine surface rupture hazards and to identify those areas at risk. This understanding can help to develop remedial measures for both structural and geotechnical engineering. For that purpose, damage to highway bridges during the recent events was reviewed. The total collapse of the highway overpass in Arifiye, during the Kocaeli earthquake, was investigated. The major problems under consideration (in Arifiye) were: (i) dislodging of the bridge spans, and consequently, the total separation of the reinforced concrete girders from the piers; and (ii) the stability of a mechanically stabilized earth wall (MSEW) system under extreme loading conditions. The results of the structural and geotechnical investigations presented herein can be taken in consideration to improve transportation infrastructure against surface rupture hazards. 相似文献
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Abstract. Scanning electron microscopy-cathodoluminescence (SEM-CL) imaging of vein quartz in the Cu-mineralised, Shuteen Complex (South Gobi, Mongolia) has revealed a complex history of crystal growth, dissolution and microfracture healing, associated with several hydrothermal events that could not be detected using other observational techniques (e.g. transmitted/reflected light microscopy, back-scattered electron imaging, or secondary electron imaging).
The quartz initially grew as CL-bright/grey crystals in a 345±30C liquid reservoir, as inferred by the analysis of primary liquid fluid inclusions (average Th of 343C; 6.6∼7.7 wt% NaCleq ). Quartz precipitation occurred at the edge of the crystals as reservoir fluids cooled to 260±25C, as indicated by micron-scale CL-dark/CL-bright quartz growth bands containing abundant fluid inclusions (with an average Th values of 261C). Pressure fluctuations were the likely cause of dissolution, as SEM-CL imaging reveals the quartz have corroded or rounded crystal edges, and precipitation of later quartz into open space. SEM-CL imaging shows the quartz contains healed microfractures that trapped low salinity fluids (3.9 wt% NaC1eq ) with Th values of 173±15C.
SEM-CL imaging provides a means of deciphering the thermal and chemical evolution of the fossil Shuteen hydrothermal system, and the nature of hydrothermal quartz vein-forming processes, by facilitating the correlation of distinct fluid inclusion populations and their relative chronology, with specific hydrothermal events. 相似文献
The quartz initially grew as CL-bright/grey crystals in a 345±30C liquid reservoir, as inferred by the analysis of primary liquid fluid inclusions (average Th of 343C; 6.6∼7.7 wt% NaCl
SEM-CL imaging provides a means of deciphering the thermal and chemical evolution of the fossil Shuteen hydrothermal system, and the nature of hydrothermal quartz vein-forming processes, by facilitating the correlation of distinct fluid inclusion populations and their relative chronology, with specific hydrothermal events. 相似文献