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61.
地质雷达在隧道检测中的应用 总被引:3,自引:0,他引:3
隧道施工完成后用常规方法很难对衬砌质量做出系统评价,地质雷达利用超高频脉冲电磁波探测目标介质的介电常数,很容易掌握砼衬砌结构的厚度、衬砌周围回填及空隙情况,围岩断层裂隙构造情况等,为工程技术评价提供依据。文章以实例,介绍了利用地质雷达对隧道进行检测所使用的仪器、工作参数及地质雷达资料处理解释步骤,并通过对几幅典型雷达图像进行分析介绍了不同异常结构在雷达剖面上的反映。 相似文献
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近间距并行管线探测方法的效果对比 总被引:4,自引:0,他引:4
介绍了管线探测的几种方法,结合实例,对近间距并行管线的几种探测方法的效果进行了比较。 相似文献
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This paper describes the use of a backprojection algorithm to reconstruct subsurface images of the electrical resistivity in horizontal planes parallel to the surface. The algorithm can be applied to detect buried objects such as tanks or pipes and possible leakages from them. Two imaging strategies are compared: juxtaposition of vertical planes, and 3D reconstruction from the sensitivity matrix corresponding to the entire volume whose surface is explored. The electrode arrays used for voltage measurement are the dipole–dipole array and a modified Schlumberger array. A personal computer controls current injection, electrode switching, and voltage detection. The system injects 1 kHz, 20 V peak-to-peak square waveforms, thus avoiding electrode polarization effects. Experimental laboratory measurements show that the algorithm detects localized objects such as an insulating sphere and a conductive cylinder immersed in water. Furthermore, covering half of the cylinder by a rubber sleeve to simulate a nonconductive leak, yields a distinct image for the leak. The backprojection algorithm does not need any regularization parameter and it is very fast in inverting the sensitivity matrix because it approximates the inverse matrix by its transposed. The dipole–dipole array usually yields a lower overall pixel error than the modified Schlumberger array but both allow the detection of simulated underground leaks. 相似文献
66.
ZHANGQiaoping IsabelleCouloigner 《地球空间信息科学学报》2004,7(2):89-95
This paper presents a tramework for road network change detectlon In order to upctate the Canadian National Topographic DataBase (NTDB). The methodology has been developed on the basis of road extraction from IRS-pan images (with a 5.8 m spatial resolution) by using a wavelet approach. The feature matching and conflation techniques are used to road change detection and updating. Elementary experiments have showed that the proposed framework could be used for developing an operational road database updating system. 相似文献
67.
GIS数据辅助下的线状目标自动提取 总被引:2,自引:0,他引:2
首先介绍了遥感影像中线状目标骨架自动提取的意义和研究现状,然后结合老的GIS数据,提出了一种算法来实现遥感影像中线状目标骨架的自动提取,算法主要包括影像预处理、GIS数据与影像的配准、骨架跟踪、编组连接与数据简化等步骤。最后又利用遥感影像和相应的GIS数据进行了实验,实验证明了算法的可行性和有效性。 相似文献
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This paper examines the transport of calcareous sand in unidirectional flow and its prediction through existing sediment transport models. A flume experiment of four sand samples collected on Oahu, Hawaii, provides 29 sets of sediment transport data in the bed-form and suspended transport stages. The measured transport data are compared with direct predictions from four energy-based transport models developed for siliceous particles. Corrections for the grain-size, fall velocity, and critical velocity of calcareous sand based on recent research are applied to the models and the results are compared with the direct calculations and measured data. The comparison illustrates the important role particle shape plays in the transport of calcareous sand. All four sediment transport models give consistent predictions and good agreement with the majority of the measured data. Two of the models respond positively to the corrections in both the bed-form and suspended transport stages indicating that such an approach may provide an interim solution for the transport of calcareous sand. 相似文献