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Different geophysical exploration methods have significant differences in terms of exploration depth,especially in frequency domain electromagnetic(EM)exploration.According to the definition of skin depth,this difference will increase with the effective detection frequency of the method.As a result,when performing three-dimensional inversion on single type of EM data,it is not possible to effectively distinguish the subsurface geoelectric structure at the full scale.Therefore,it is necessary to perform joint inversion on different type of EM data.In this paper we combine the magnetotelluric method(MT)with the controlled-source audio-magnetotelluric method(CSAMT)to study the frequency-domain three-dimensional(3D)joint inversions,and we use the unstructured finite-element method to do the forward modeling for them,so that the numerical simulation accuracies of different electromagnetic methods can be satisfied.By combining the two sets of data,we can obtain the sensitivity of the electrical structure at different depths,and depict the full-scale subsurface geoelectric structures.In actual mineral exploration,the 3D joint inversion is more useful for identifying subsurface veins in the shallow part and blind mines in the deep part.It can delineate the morphological distribution of ore bodies more completely and provide reliable EM interpretations to guide the mining of minerals. 相似文献
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使用搭载200&400 MHz复合天线的LTD系列探地雷达,对埋设的未爆弹进行探测试验,并运用克希霍夫积分偏移法及三维插值算法对探地雷达数据进行三维成像。试验结果能准确地反映出浅埋未爆弹的位置信息,可指导排爆人员进行精确的开挖及排除。 相似文献
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近年来,探地雷达被越来越多地应用于考古探查中。由于反演多解性问题的存在,雷达图像上的异常既可能是考古目标引起的,也可能是由于地下环境介质的不连续性引起的,所以探究不同类型的考古遗存在探地雷达图像上的典型异常响应,有助于准确识别雷达图像上的“真”异常,剔除一些“假”异常。首先,本文基于西北干旱-半干旱区文物埋藏环境,在河北省怀来县遥感综合试验站试验区设计实施了地下目标体探地雷达探测实验,分析了不同材质的小尺度目标体及夯土结构在探地雷达图像上的响应特征;然后,进一步将探地雷达应用于悬泉置遗址地下城墙基址的探测,对城墙在雷达图像上的响应特征进行了分析。实践表明,探地雷达技术在埋藏浅、小尺度、物性差异不大的考古探查中具有很好的效果,得到并解释了点状、线状、面状等不同考古目标体在探地雷达图像上的响应规律。 相似文献
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基于含油污水管道内输送液体温度高、无压和检测区域面层为硬化混凝土的特点,对某厂区含油污水铸铁管道地下渗漏问题,利用探地雷达方法进行了探测。分析表明,污染物在地层中的扩散形态、污染物与孔隙水的导电性和综合介电常数是影响探测结果的主要因素,而这些因素又受到土层孔隙度、饱和度和污染物与孔隙水的相互作用影响,从而改变了土壤污染区的物理和化学性质。在综合分析获得的不同类型渗漏污染源引起的异常特征前提下,将探地雷达剖面划分成三大类型,并依据这些典型图谱特征,圈定了渗漏点并得到了验证,研究结果证实了探地雷达方法对此类特殊污染物和污染区探测的可行性。 相似文献
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1 IntroductionSeaice ,asanimportantcomponentoftheArcticclimatesystem ,hasdrawnsignifi cantscientificinterest.Seaicethicknessanditsmorphologyhavedramaticimpactsono cean atmosphere iceinteractions(Wadhams 1 994;Barryetal.1 993 ;Dickson 1 999;PadhamsandNorman 2 0 0 0 ) ,whichdirectlyaffecttheexchangeprocessandspeedofheatandmassbetweentheoceanandtheatmosphere ,dominatethephysicalmechanicsfea turesofseaice ,andaffecttheseaicemovement&deformationaswellasicefreezing&meltingprocess(Hollandetal.1 99… 相似文献
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Analysis of multi-dimensional SAR for determining the thickness of thin sea ice in the Bohai Sea 总被引：1，自引：0，他引：1
Flat thin ice (<30 cm thick) is a common ice type in the Bohai Sea, China. Ice thickness detection is important to offshore exploration and marine transport in winter. Synthetic aperture radar (SAR) can be used to acquire sea ice data in all weather conditions, and it is a useful tool for monitoring sea ice conditions. In this paper, we combine a multi-layered sea ice electromagnetic (EM) scattering model with a sea ice thermodynamic model to assess the determination of the thickness of flat thin ice in the Bohai Sea using SAR at different frequencies, polarization, and incidence angles. Our modeling studies suggest that co-polarization backscattering coefficients and the co-polarized ratio can be used to retrieve the thickness of flat thin ice from C- and X-band SAR, while the co-polarized correlation coefficient can be used to retrieve flat thin ice thickness from L-, C-, and X-band SAR. Importantly, small or moderate incidence angles should be chosen to avoid the effect of speckle noise. 相似文献
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《世界地质(英文版)》2015,(3)
The ground penetrating radar( GPR) detection data is a wide band signal,always disturbed by some noise,such as ambient random noise and multiple reflection waves. The noise affects the target identification of underground medium seriously. A method based on principal component analysis( PCA) was proposed to extract the target signal and remove the uncorrelated noise. According to the correlation of signal,the authors get the eigenvalues and corresponding eigenvectors by decomposing the covariance matrix of GPR data and make linear transformation for the GPR data to get the principal components( PCs). The lower-order PCs stand for the strong correlated target signals of the raw data,and the higher-order ones present the uncorrelated noise.Thus the authors can extract the target signal and filter uncorrelated noise effectively by the PCA. This method was demonstrated on real ultra-wideband through-wall radar data and simulated GPR data. Both of the results show that the PCA method can effectively extract the GPR target signal and remove the uncorrelated noise. 相似文献
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Fracture is a common underground structure phenomenon, which can provide space and passage for the storage and migration of oil and gas. Borehole radar is a fast and high-resolution geophysical detection method, which has been widely used in engineering, exploration and other fields. This paper mainly uses theoretical analysis and numerical simulation to study the variation law of the characteristics of the received borehole radar signal with the variation of fracture width. The Ricker wavelet is used as the pulse signal of the borehole radar. The results show that the amplitude of the signal received by the borehole radar first increases, then decreases, and finally tends to be a stable value with the increase of fracture width. The results have guiding significance for the detection of underground fractures and the estimation of fracture width by borehole radar. 相似文献
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水下的地质雷达探测与常规的地质雷达探测具有显著的不同点。文中对CPML吸收边界条件的公式进行推导,并通过数值模拟对均匀介质以及非均匀介质中吸收边界条件的吸收效果进行了验证,数值模拟的波场快照证明了CPML吸收边界条件在水下的地质雷达数值模拟中具有很好的吸收效果。通过对水平层状介质模型以及倾斜层状介质模型开展数值模拟,并结合实际探测的雷达图像,证明地质雷达对于水下地层的探测能够取得良好的效果;通过对空洞体位于不同深度时的数值模拟,证明了地质雷达对于水下的空洞探测也能对其位置及规模进行较为准确的判断。这为水下地质灾害的探测提供了理论依据及指导。 相似文献
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Wang Fan Wang Jianing Xu Lijun Zhang Xiangguang Yan Shefeng Chen Yonghua 《中国海洋湖沼学报》2020,38(4):1080-1091
Subsurface mooring allows researchers to measure the ocean properties suchas water te mperature,salinity,and velocity at several depths of the water column for a long period.Traditional subsurface mooring can release data only after recovered,which constrains the usage of the subsurface and deep layer data in the ocean and climate predictions.Recently,we developed a new real-time subsurface mooring(RTSM).Velocity profiles over upper 1 000 m depth and layered data from sensors up to 5 000 m depth can be realtime transmitted to the small surface buoy through underwater acoustic communication and then to the office through Beidou or Iridium satellite.To verify and refine their design and data transmission process,we deployed more than 30 sets of RTSMs in the western Pacific to do a 1-year continuous run during2016-2018.The continuous running period of RTSM in a 1-year cycle can reach more than 260 days on average,and more than 95% of observed data can be successfully transmitted back to the office.Compared to the widely-used inductive coupling communication,wireless acoustic communication has been shown more applicable to the underwater sensor network with large depth intervals and long transmission distance to the surface. 相似文献
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利用Bedmap2数据与中国第29次南极科学考察期间获取的冰雷达数据,在中山站至Dome A断面的Gamburtsev山脉地区首次构建11.3 km×11.5 km南极局部冰盖三维模型。着重介绍三维模型建立过程中的数据处理,其中冰雷达数据采集首次采用中国自主研发的冰雷达系统。详细阐述了冰雷达数据的处理流程,包括数据预处理、常规图像修正技术以及冰下地形获取,得到冰下基岩埋深和冰盖内部等时层埋深,插值得到100 m分辨率的冰下基岩DEM（海拔1 729 m~2 718 m）和等时层DEM（海拔2 601 m~2 950 m）,利用南极Bedmap2冰表面栅格影像得到100 m分辨率的冰盖表面DEM（海拔3 679 m~3 745 m）。结合冰盖内外部数据处理结果,构建包含冰盖表面、冰盖内部等时层和冰下基岩地形特征的三维模型,并对模型进行检验,对冰盖内外部地形特征进行初步分析。 相似文献
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以黔东北锰矿矿集区的李家湾-高地-道坨超大型"大塘坡式"锰矿床为例,探讨了在开展勘查地质大数据的特征和结构分析的基础上,厘定事实表和维度表,进而通过对勘查数据的收集、提取、ETL操作,并应用OWB工具建立锰矿山勘探数据的数据集市的思路与方法。进而探讨了以所建立的数据集市为数据支撑平台,建立黔东北超大型锰矿床高精度三维地质模型的途径。该矿床三维地质模型汇集了海量的空间数据与属性数据,是锰矿矿山异质异构勘查开发大数据的有效载体。基于该精细、全息的矿床三维地质模型,不但可以直观反映矿床和矿体特征,而且可以作为矿山管理及其深部和外围找矿预测的可视化分析工具。 相似文献
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With the development of gravity gradient full tensor measurement technique , three-dimensional (3D) inversion based on gravity gradient tensor can provide more accurate information .But the forward calcula-tion of 3D full tensor sensitivity matrix is very time-consuming, which restricts its development and application . According to the symmetry of the kernel function , the authors reconstruct the underground source of geological body to avoid repeat computation of the same value , and work out the corresponding relationship between the re-sponse of geological body to the observation point and the response of reconstructed geological body to the obser -vation point .According to the relationship , rapid calculation of full tensor gravity sensitivity matrix can be achieved .The model calculation shows that this method can increase the speed of 30-45 times compared with the traditional calculation method .The sensitivity matrix is applied to the multi-component inversion of gravity gradient .The application of this method on the measured data provides the basis for the promotion of the meth -od. 相似文献
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《中国海洋大学学报(英文版)》2019,(6)
This paper proposes a new method for data assimilation of the surface radial current observed by High Frequency ground wave radar and optimization of the bottom friction coefficient. In this method, the shallow water wave equation is introduced into the cost function of the multigrid three-dimensional variation data assimilation method as the weak constraint term, the surface current and the bottom friction coefficient are defined as the analytical variables, and the high spatiotemporal resolution surface radial flow observed by the high-frequency ground wave radar is used to optimize the surface current and bottom friction coefficient. This method can effectively consider the spatiotemporal correlation of radar data and extract multiscale information from surface radial flow data from long waves to short waves. Introducing the shallow water wave equation into the cost function as a weak constraint condition can adjust both the momentum and mass fields simultaneously to obtain more reasonable analysis information. The optimized bottom friction coefficient is introduced into the regional ocean numerical model to carry out numerical experiments. The test results show that the bottom friction coefficient obtained by this method can effectively improve the accuracy of the numerical simulation of sea surface height in the offshore area and reduce the simulation error. 相似文献
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"bright spot" on reflection seismic profile has been regarded as one of the important indications of oil and gas, and it has been widely used in the oil and gas exploration.Moreover, with the development of new technologies, "bright spot" technique has been gradually applied to the exploration of coal, underground water and other fields, and also in the research of deep structure of the earth.Based on the reviewing of published literatures, the authors described the structural features and generation of "bright spot" on seismic profile for energy resources exploration and crustal-scale deep seismic reflection profiles, and further summarized the applications of the "bright spot" technique in energy resource exploration and deep structure research. 相似文献
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《世界地质(英文版)》2016,(2):117-124
It is important to know the shape and distribution of sandstone bodies in the subsurface when forma-tion and migration of a dune model are determined.The information plays a significant role in identification of the continental oil and gas accumulation.In this study,the combination of ground penetrating radar (GPR) and electrical resistivity tomography method (ERT)is used in mapping the distribution of sandstone bodies in Yanchang Formation.Six GPR profiles and seven ERT profiles are used to analysis.GPR data show clear re-flections from the top interface of sandstones.ERT data show a continuous high resistivity anomaly correspon-ding to the sandstone body.Combined the reconstructed 3D images by GPR and ERT,the spatial distribution of sandstone bodies is described. 相似文献
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某建筑用地位于原瓦庄煤矿矿界范围内，场地及周边曾进行过多期次的煤矿资源开采活动，形成诸多煤矿采空区，且有一封闭的瓦庄煤矿斜井待探查。通过现场踏勘、资料收集、分析及研究，采用高密度电阻率法和地质雷达综合地球物理方法对采空区进行勘察，重点探测废弃巷道的位置、埋深及走向等信息。根据探测目的要求，设计高密度测线2条、雷达测线6条，分别采用频率为100MHz和40MHz雷达天线进行现场探测，获取了地下0~30.0m深度范围的地质信息，查明了废弃巷道的分布范围、埋深及走向，后经钻探验证，采空区特征参数准确。本次探测成果为未来进行浅地表非积水高阻采空区的探查提供了基本思路与技术方法，同时也为后续场地稳定性及建筑适宜性评价提供了基础资料。 相似文献