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本文将“压缩恢复法”应用到钻孔电磁波勘探中,并通过建立两个数字化图像模型予以计算机实现。与非压缩法比较,可以看出“压缩恢复法”有一定效果。 相似文献
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简要叙述了电磁波CT成象技术的基本原理、工作方法及其在岩土工程中诸如机场跑道、隧道工程和高层建筑地基评价中的应用。通过井下激发和观测电磁波能量的衰减,利用CT技术重建了地下介质在观测平面内相对吸收系数的二维分布图象,这些图象直观准确地反映出地下介质的构造形态、地层界面、风化壳以及破碎带的分布特征,在岩土工程探测中发挥了重要作用。 相似文献
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郭履灿 《CT理论与应用研究》2002,11(3):49-51
作者应德国汉堡大学杜达教授的邀请,并获得马克斯-普朗克基金会的资助,于2002年6-8月,在德国访问了五个地球科学机构,就所见所闻并结合与地球CT的文献和网站的资料,初步综述如下,今后本刊将分专题进行补充报道. 相似文献
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杨占宝 《地震地磁观测与研究》2004,25(3):63-67
随着现代科学技术的发展,数字化地震监测技术正在我国得到逐步普及。根据胜利油田的实际情况,作者对胜利油田深井数字化地震监测系统建设中主要考虑的影响因素、系统功能、技术方案和设备选型、系统特色、观测结果及应用等方面进行了深入的研究。经过4年多的运行证明,该系统建设功能齐全、先进,地震事件处理便捷、定位准确,对山东省尤其是渤海强震区的地震监测发挥了重要作用。 相似文献
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井间电磁波CT技术是利用地层间介质的物性差异,不同性质的物质对电磁波的反射和吸收能力是不同的。井间电磁波CT技术在探测岩溶裂缝等方面有较好效果,本文利用井间电磁波CT技术,对昆明地铁四号线苏家塘站岩溶专项线路工程地下岩溶发育地段进行测试,通过对工区岩石电磁波吸收系数差异的研究,依据吸收系数特征,探测到地铁线路工程地下岩溶及裂缝发育,划分出4个层次的岩溶区,经与钻孔岩心资料对比,证实探测结果的正确性。且对工程设计和施工提供了必要的基础资料。 相似文献
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Field measurements of settling velocities of fine sediments in Three Gorges Reservoir using ADV 总被引:1,自引:0,他引:1
《国际泥沙研究》2016,(3):237-243
The Three Gorges Reservoir (TGR) is suffering from unexpected fine sediment deposition, to better understand the fine sediment transport processes, field measurements were conducted at the Zhongxian and Fengjie reaches. A method based on the sediment diffusion equation was proposed to measure the settling velocities using the Acoustic Doppler Velocimeter (ADV). The backscatter acoustic intensities (BSI) received from the ADV were calibrated against the sediment concentrations measured via water sampling, suggesting a linear relationship in double logarithmic coordinate system. The instantaneous sediment concentration was calculated using the derived relationship, and then the settling velocity was obtained through the proposed procedure. The settling velocities of the fine particles in the TGR were found to vary with the water depth. Most of the effective settling velocities were within the range of 0.1–10 mm/s, which were larger than those of the primary particles, indicating that the flocculation was likely to occur in the TGR. Additionally, it is suggested that the turbulent motion played an important role in the flocculation in the TGR. 相似文献
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CT在岩土实验中的数值分析 总被引:14,自引:0,他引:14
本文利用CT对岩石、土壤、水体多种成分的冻结过程进行了实验研究。阐述了X射线与物质的相互作用,CT检查实验样品的数学原理。对图像的分辨率和伪影进行了讨论,对实验样品的最佳扫描条件进行了分析。为了定量分析岩土CT图像,以便深人地动态研究在不同实验过程中土样内部组织结构的变化,物质成份的迁移,需要针对扫描样品建立数值方程。通过对各种形状、尺寸、密度和组分的标准样品进行大量的CT扫描,对理论方程进行了验证。对扫描数据的统计分析说明,CT值随物质密度增加而线性增加,其斜率与物质成份有关;对于高密度的物质,CT值随着样品直径的减小而增加。为了以统一的数学模型描述实验样品的CT值,对理论公式进行调整、建立了半经验数值方程。利用数值方程可以定量分析岩土样品在冻结过程中的水份迁移,冻结澎胀变形;在外力作用下组织结构的变化;在温度变化过程中在冻结层面及未冻水的含量;在自然状态中材料的孔隙度等等工程科学研究中的问题。实验证明,CT用于岩土及其它材料科研中具有较高的价值。 相似文献
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行星地震能够在大气中激发声波,该波动携带地震信息在大气中上传,可以作为行星地震监测研究的示踪目标.本文研究了不同频率的声波,在金星背景大气条件下的上传特征.通过计算大气密度分布、大气黏滞性和热传导效应引起的声波振幅变化,得到不同频率声波的振幅高度剖面.研究发现低频声波能够上传到较高高度,且振幅出现显著放大.根据振幅的高度分布以及金星光学辐射特征可以得到,通过光学遥感的方式探测金星声波扰动时,所选波段对应的辐射高度应为90 km附近及以上,并据此筛选了探测的可用频段.该研究结果为金星地质活动光学遥感探测的参数选择提供了参考.
相似文献18.
There are several levels of models for the snowmelt process in terms of the snow thermal structure: isothermal, bi-layered and multi-layered models. However, it is difficult to choose the appropriate level of complexity for application because the number of unknown variables is crucial in model handling. One of the major issues in energy balance snow models is the shape of the snow temperature vertical profile. This profile, if taken as a specified function, would simplify a snowmelt model calibration and computation significantly. In this study, in order to determine the appropriate representative snow vertical thermal profile, snow temperature measurements have been performed using five snow thermocouples placed vertically along an observation tower with insulating arms. Also, as a field experimental study of an energy balance snow model, the net radiation, air temperature, relative humidity and wind speed along with the vertical one dimensional snow temperature profile have been observed at a field site in Lake Tahoe Basin. The computational results correspond with the measured snow temperature profile and snow water equivalent reasonably well. It is illustrated that the temperature in the snow near surface (called the “active layer”) varies daily, and the lower snow layer (called the “inactive layer”) is barely affected by the atmosphere. The results of field observations and the numerical experiments show that the vertical temperature distributions in the active layer, which is the upper layer affected by energy exchange with the atmosphere, generally have an exponential shape during night time under cold weather, while snow pack stays around 0 °C during daytime. Both of the results indicate that not only the snow temperature in the top active layer, but also the thickness of snow active layer fluctuates during the snowmelt process. The observation results show that the thickness of the active layer may reach about 60 cm in Sierra Nevada, California. These results provide significant information for the development of appropriate approximations in physically based snowmelt modeling. 相似文献
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