高密度电法在探测隐伏断裂带中的应用

本文介绍了高密度电法的原理及工作方法,并应用高密度电法对龙门山断裂区的隐伏断裂带进行了勘测。实验结果表明了高密度电法,是探测隐伏断裂带的行之有效的方法。     

综合物化探方法探测沙湾隐伏断裂带中段

沙湾断裂带是珠江三角洲内的一组NW向断裂带,出露较少,以隐伏为主。在本次隐伏断裂探测过程中,采用了浅层地震反射波法、高密度电法及土壤氡气法,对沙湾断裂带中段隐伏断裂---大乌岗断裂、沙湾断裂、陈村断裂、紫坭断裂进行了综合探查,共发现7处异常,初步查明沙湾断裂带的通过位置等几何信息,为进一步进行钻孔验证奠定基础。     

综合物探方法在福州长乐地区地壳稳定性评价中的应用

在地壳稳定性评价中运用地球物理勘探方法探测隐伏断裂构造行之有效。单一物探方法的使用存在较多局限,综合物探方法的运用体现了其优越性和可靠性。福州市长乐地区通过开展高精度磁法、高密度电法、可控源音频大地电磁测深(CSAMT)法、浅层地震反射法等综合物探方法测量,查明了区内2条北北东向隐伏断裂构造位置及空间分布特征,体现了综合物探方法在断裂构造探测领域的有效性。     

高密度电法在内蒙古喀喇沁旗毛林坝萤石矿找矿中的应用

高密度电法是浅层地球物理勘查的主要方法之一,已广泛应用于工程勘察、矿产资源勘查、工程质量检测、考古、煤炭采空区勘查、水利水电工程和环境等领域。基于内蒙古喀喇沁旗大西沟一带萤石矿调查成果,以毛林坝低温热液裂隙脉状充填萤石矿为例,运用高密度电法对该矿体南西延伸隐伏地区进行了探测。结果表明,在萤石矿控矿断裂南西隐伏延伸部位,高密度电法剖面均显示有低阻异常。经槽探工程揭露,地表浅部矿体达工业规模,大致查明了控矿断裂的延伸情况,为下一步深部钻探工程布置指明了方向,同时为热液裂隙充填型萤石矿床勘查工作提供参考。     

高密度电法探测基岩起伏和隐伏断裂中的应用

蓟县山前地带兴建高档住宅小区,勘察过程中发现基岩埋深变化较大,采用高密度电法进行探测,根据视电阻率等值线的变化规律较好地解决了这一问题,同时对测区内可能存在的隐伏断裂进行了分析判断。     

综合物探技术在北京山前平原隐伏断层探测中的应用

复杂地质隐伏断层探测是地球物理勘测难点之一。本文介绍了高密度电法、浅层地震反射波法、可控源音频大地电磁测深法在北京山前平原隐伏断层综合探测的应用。在北京山前平原复杂地形条件下,综合物探技术方法对隐伏断层的探测具有可靠和成果直观的特点。     

基于高密度电法的城市岩溶地下水通道三维电性成像

岩溶地下水通道是隐伏岩溶区常见的地质现象,开展城市隐伏岩溶通道探测对城市地下空间开发和地质灾害防治具有重要意义。岩溶通道常具有高度的空间变异性,常规二维探测难以对其进行较好的表征。基于此,文章采用三维高密度电法对城市隐伏岩溶地下通道进行了精细探测,结合地球物理数值模拟和应用实例,分析三维高密度电法对不同充填类型岩溶地下通道的成像效果。结果表明：三维高密度电法较二维探测在数据量和分辨率上均有较大提升,可更直观地表征目标体三维电性结构特征,该探测方法对岩溶地下水通道成像具有优势;通过对武汉市源泉村岩溶地下水通道三维电性成像,揭示了该低温热泉的地下水运移特征,可为城市地热勘探开发提供参考。     

综合物探方法在广西罗城县活动断裂鉴定中的应用

城市活动断层探测在城市发展建设过程中和保障人民生命财产安全方面起到重要作用。本文以鉴定罗城断裂和上天桥—寺门断裂活动性为目的,在地震地质调查确定其断裂的几何学、运动学和年代学的基础上,选择第四系覆盖断裂最有可能活动的地段,重点采用高密度电法和地震映像方法来探测断裂在隐伏地段的具体位置,通过排钻验证,以及揭露其断裂与第四纪覆盖层之间的错断关系,来确定其断裂最新活动年代。结果表明,高密度电法和地震映像综合物探方法准确探测到了罗城断裂和上天桥—寺门断裂在隐伏地段的位置,且钻孔岩心中断裂面、断裂擦痕、断裂碎裂岩和构造角砾岩等发育,但断裂未错断第四系覆盖层,从而确定其断裂活动年代为早更新世。根据相关规范要求,罗城断裂和上天桥—寺门断裂全新世以来不活动,罗城县的建设规划可不采取避让措施,该鉴定结果为今后罗城县的工程建设提供了安全保障。     

高密度电法岩溶探测模型及其在变电工程中的应用

在我国西南部,由于地质条件复杂,许多变电工程不可避免地建于岩溶发育地区,因此探明站址底部隐伏岩溶的位置、规模、埋深及充填物是工程勘察的重点。采用高密度电法进行探测,通过数值模拟计算,总结分析不同填充类型岩溶的地电响应特征,为现场探测、分析、解释溶洞特征提供科学依据;结合站址底部隐伏岩溶探测工程案例,说明高密度电法能有效地查明地下隐伏岩溶,为变电工程合理选址及设计基础深度提供可靠依据。     

高密度电法在莱州留驾水库隐伏断裂构造探测中的应用

为了确定莱州市南部留架水库西岸隐伏断裂构造对留架水库蓄水的影响,通过在留架水库西岸布设高密度电阻率法测线,初步查明了留架水库西岸的地层特征、隐伏断裂构造的分布情况及水文特征。留架水库西岸地表为第四系覆盖层,深部为结构较为完整的花岗岩基岩,地层含水性较差,探测到西岸发育两条隐伏断裂构造,其中F1断裂构造走向南东规模较大且富水性较好,F2断裂构造走向北东规模较小且富水性较差,F1断裂内赋存的裂隙水可对水库库容进行有效地补给,有效缓解留驾水库的蓄水压力。本文实例表明,对于围岩有明显电性差异的具有一定规模的断裂构造,高密度电阻率法是一种有效的探测方法。     

高密度电法评价岩溶地下水分布

本文利用高密度电法对第四系土层进行了勘查,利用所得到的高密度电阻率反演剖面资料,进行了分析,切片,形成等深度的高密度电阻率勘查反演电阻率平面分布,推断地下水的空间活动规律。对利用高密度电阻率勘查推断地下水的空间活动规律进行了一次有益的尝试,为进一步认识地面塌陷和预防治理提供科学依据。     

A numerical comparison of enhancing horizontal resolution (EHR) technique utilizing 2D resistivity imaging

The effectiveness of inversion apparent resistivity data to determine accurately the true resistivity distribution over 2D structures has been investigated using a common inversion scheme based on smoothness-constrained nonlinear least-squares optimization with enhancing horizontal resolution (EHR) technique by numerical simulation. The theoretical model generates in RES2DMOD software at specific distance and depth using Wenner, Wenner–Schlumberger, and pole–dipole arrays were inverted. The inversion model was compared with the original 2D model in RES2DINV software. The study model includes horizontal layering, vertical resolution, and horizontal two layers with different resistivity. Also, the response to variations in data density of these arrays was investigated. The study shows the best array suitable to be used in the survey was chosen for real data acquisition at the actual site. Subsequently, the results from borehole were used to verify the results of 2D resistivity imaging method with and without EHR technique. Saturated zone (0–40 Ω-m) was found scattered at the depth of 10–20 m. The borehole is located at 63 m at 2D resistivity imaging survey which shows at depth 10–20 m is sandy silt. Highly weathered sandstone was found at 6 m depth with resistivity value of 800 Ω-m and SPT N value of 20. The bedrock was found at 27 m depth with resistivity value of 3,000 Ω-m and SPT N value of 50. The application of 2D resistivity imaging with EHR technique indicate the ability of the proposed approach in terms of density, depth, and resistivity value of anomalous and layer in a computationally and numerically efficient manner and to exhibit good performance in the data inversion.     

高密度电法的发展与应用

文中从电极排列、反演处理方法、仪器等几个方面 ,介绍了高密度电法的发展 ,说明了所有电极排列方式是从对称四极、单极偶极和单极单极发展而来。在反演方法软件方面 ,介绍了基于圆滑约束最小二乘法及计算机反演快速计算程序。同时 ,提出供电时间、极化补偿和电极转换开关是高密度电法仪器发展的关键技术。文中列举了高密度电法在多个领域的应用简况 ,最后提出了高密度电法在今后发展的趋势为高密度激发极化法、三维高密度电阻率法。     

Geophysical-geochemical investigation of fire-prone landfills

This paper deals with the integration of electrical resistivity tomography and geochemical methods for studying four different fire-prone landfills. Landfill gas composition (CH₄, H₂S, O₂, CO, CO₂) and subsurface temperature were measured with the constant net 50 × 50 m from the depth 10–60 cm. 28 electrical resistivity tomography lines were surveyed, while Wenner and Sclumberger electrode arrays were employed for all measurements. At the studied sites the landfill gas and temperature measurements mapped gas and temperature anomalies over underground fire sources. 2D electrical resistivity tomography lines, performed over these anomalies, showed these fire sources as high-resistivity zones. The joint employment of the electrical imaging and geochemical survey seems to be a useful tool in carrying out diagnostic investigations at fire-prone landfills.     

Evaluation of landfill disposal boundary by means of electrical resistivity imaging

This paper deals with an employment of electrical resistivity imaging (ERI) for survey of leachate content on the waste disposal site in Northern Israel. The research consisted of conducting ten ERI lines and drilling investigation wells. Data simulation used a 2D EarthImager inversion program. Analysis of 2D ERI interpretation results shows that determination of the boundary between the landfill body bottom intensively saturated with leachates and underlying layers of highly water saturated fat nonconsolidated clays presents a challenge. However, statistical analysis of ERI data indicates that standard deviation and confidence interval of a set of resistivity data measured in the landfill body are significantly larger than those in underlying clays. Moreover, maximum changes of these parameters are found on the boundary between landfill body and underlying soil, thus reflecting natural differences in scattering of resistivity data measured in these two objects.     

Geoelectric stratigraphy and subsurface evaluation of quaternary stream sediments at the Cooper Basin,NE Texas

An electrical resistivity survey of a portion of the Cooper Reservoir Basin in northeast Texas has been used to delineate the major lithostratigraphic units of Quaternary flood plain deposits and subsurface paleogeomorphic features of interest to geoarchaeologists. This investigation was conducted to evaluate the fluviatile deposits along the South Sulphur River which flows through Cooper Basin, to identify the basin morphology, and to detect buried geomorphic features. Buried stream channels were considered to be important targets since buried prehistoric site locations are thought to be related to patterns of fluvial facies. Two general techniques were used in the survey. First, soundings were conducted over borehole locations to correlate lithologies with resistivity variations. Second, multiple resistivity profiles were established along traverses across the flood plain. By repeating each traverse but with increased probe separations, a composite of profiles was developed yielding electrical cross-sections of the subsurface. These cross-sections were then interpreted in terms of the lithologic stratigraphy in the basin. Sounding data were evaluated using empirical methods, and profile data were evaluated qualitatively. the sounding data defined the major resistivity horizons which correlate to the primary sedimentary units in the Cooper Basin. Profile data, used to construct resistivity cross-sections, revealed a series of buried erosional features interpreted as channel segments and allowed for the estimation of relative time boundaries within sediments buried under the flood plain as the basin evolved.     

Comparison between 2D imaging and vertical electrical sounding in aquifer delineation: a case study of south and south west of Samawa City (IRAQ)

The vertical electrical sounding (VES) survey was carried out by using Schlumberger array in (12) points distributed along two profiles, except VES 6 was not located within any profile. The 2D imaging survey was carried out using Wenner array in four stations. The VES results revealed the presence of two groundwater aquifers. The first is Euphrates aquifer and the second is Dammam aquifer. While the results of 2D imaging survey distinguished two secondary aquifers in addition to previous aquifers located within Dammam formation. Also, 2D imaging gave a more accurate picture for the distribution of electrical horizons especially for the depths which ranges between 2.5 and 73 m. While the VES gives information for larger depths than that of 2D, which ranges between the earth’s surface and a depth 140 m. The geo-electrical sections of VES showed electrical horizons (layers) with sharp boundaries. But the 2D inverse models revealed the lateral and vertical variations of the resistivity within each horizon especially for shallow depths due to large volume of data available in 2D measurement. These variations were not shown in the geo-electrical sections of VES points. Comparison of VES and 2D imaging techniques revealed that the 2D imaging was the best for determined the shallow aquifers as observed from this study. It can be concluded that 2D resistivity imaging and VES can provide very useful guide for borehole drilling particularly where there is no existing well.     

高密度电法在厦-成高速公路段四川大田头大桥勘察中的应用

高密度电法是一种以地球物理为基础,集电剖面和电测深为一体,采用高密度布点,进行二维地电断面测量,研究地下介质体电阻率差异的一种勘查技术.在此,以厦门至成都公路四川境川黔界至纳溪段高速公路C9合同段大田头大桥为例,介绍了高密度电法的基本原理及其在勘查中的应用效果.     

Application of 2D and 3D geoelectrical resistivity imaging for engineering site investigation in a crystalline basement terrain,southwestern Nigeria

Orthogonal set of 2D geoelectrical resistivity field data, consisting of six parallel and five perpendicular profiles, were collected in an investigation site using the conventional Wenner array. Seven Schlumberger soundings were also conducted on the site to provide ID layering information and supplement the orthogonal 2D profiles. The observed 2D apparent resistivity data were first processed individually and then collated into 3D data set which was processed using a 3D inversion code. The 3D model resistivity images obtained from the inversion are presented as horizontal depth slices. Some distortions observed in the 2D images from the inversion of the 2D profiles are not observed in the 2D images extracted from the 3D inversion. The survey was conducted with the aim of investigating the degree of weathering and fracturing in the weathered profile, and thereby ascertaining the suitability of the site for engineering constructions as well as determining its groundwater potential.