Surface Geophysical Methods used to Verify the Karst Geological Structure in the Built-up Area: A Case Study of Specific Engineering-Geological Conditions

This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaská near Banská Bystrica in Slovakia. The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material. Its maximum thickness is 3 m. Another specificific condition of the study area is its location in the built-up area, due to which the applicability of geophysical methods was limited. The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill, which complicates the identification of cave spaces. The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.     

Numerical models of convection in the earth's mantle

Calculations on convection in Newtonian fluids at large Rayleigh numbers show behaviour in general agreement with geophysical observations. The calculated values of surface velocities, regional gravity and topographic anomalies all lie within the range of values found at the earth's surface. The sign of the gravity anomaly over rising fluid is positive because the gravitational effect of the surface deformation is greater than that of the density deficit. This result appears to agree with geophysical observations and should permit the flow within the mantle to be followed in some detail.     

基于综合物探方法的公路不稳定边坡潜在滑面探测

为查明公路边坡滑面分布情况,采用瞬态面波和对称四极电测深法进行综合物探勘察,成功识别出滑动面以及潜在滑面位置、形态和范围,再结合钻孔,得出滑坡体地质剖面,高效准确的为滑坡处治设计提供了基础资料。工程实例应用表明,瞬态面波成像在滑动面以及潜在滑面识别中准确直观,且可以提供波速参数;电测深法能够提供不同地质体的电阻率参数,可以对瞬态面波进行有效补充;两种方法互相结合,可以较大限度的降低物探多解性,结合少量钻孔,能提供较为准确的滑坡体地质剖面,可在公路不稳定斜坡探测中发挥重要作用。     

准噶尔盆地表层结构基本类型及特征

地震勘探区内表层及近地表结构的地球物理特征，往往取决于相应的地质体结构的变化．研究不同表层及近地表地质体的地质特征和地球物理特征，对地震勘探中静校正方法的确定以及静校正量的求取至关重要．准噶尔盆地就其表层地质结构可分为山前冲积扇、戈壁、农田、沙漠等类型，不同类型的地质结构体具有各自独特的地球物理特征。     

复杂造山带地区三维地质填图中深部地质结构的约束方法: 西准噶尔克拉玛依后山地区三维地质填图实践

在地球物理资料稀少、钻孔数据匮乏的复杂造山带地区进行三维地质填图, 目前尚处于实践探索阶段.我们的填图工作思路是: 以精细地表地质调查为基础, 在地质-地球物理-钻孔等多源数据约束下, 充分利用野外走廊带解析剖面、实测自然剖面、地球物理解释剖面等资料, 进行人机交互式三维地质建模, 并根据使用资料的准确性、空间分辨的精细程度等对模型的可靠程度进行分块评价.浅表层以地表地质信息(包括产状、地层层序关系、地层厚度、褶皱形态、断层性质与位移、局部和区域概念地质模型等)约束为主, 深部地质结构则主要依据地球物理剖面资料, 少量钻孔资料不仅用以校验地球物理资料解释的可靠性, 并对模型施加强约束.以西准噶尔克拉玛依后山地区三维地质填图为例, 着重讨论了在三维建模中如何具体实现上述思路和约束方法.实践证明, 该填图思路和建模方法是行之有效的, 可操作性强.      

浅层地震反射波法在水域地质勘察中的应用

鉴于传统钻孔勘探确定淤泥层起伏情况的不足,在某一围堤水域地质勘察中利用浅层地震反射波法,确定淤泥层的起伏情况。从本场地反射波法物探映像图中可知．淤泥层与粘土层之间的界限明显,均在30s^-3左右产生了明显的反射波,且能清楚的看到基岩面的起伏情况。经过与钻探资料的对比发现,物探结果精度较高,满足了该工程的技术要求。分析表明,浅层地震反射波法是一种速度快、效率高的水域工程物探新方法,在各种水域工程的岩土工程勘察中有着广阔的应用前景。     

基于地表地质调查剖面网络基础上的复杂造山带三维地质调查与建模方法

三维地质填图是一项探索性很强的开拓性工作,目前尚无成熟经验可循.对于地球物理和钻探资料相对有限的复杂造山带成矿带地区,区域性的三维地质结构的揭示更具挑战性.结合西准噶尔克拉玛依后山地区三维地质填图实践,提出造山带基岩三维地质填图的基本思路,对具有一定幅面一定比例尺的区域三维地质填图与建模的方法技术进行了总结,提出针对造山带区域的“基于地表地质调查剖面网络基础上的地质-地球物理-钻孔联合约束的三维地质调查方法体系”,探索实践“基于地表地质调查剖面网络基础上的三维地质建模技术方法”,强调建模的数据基础来自地表基础地质调查的系统路线剖面和实测剖面,即以地表实测地质路线为基础结合地球物理和钻探资料向下合理延拓,从而实现“区域三维地质填图”概念上的三维地质结构的数字表达.      

Structure, Composition and Evolution of the South Indian and Sri Lankan Granulite Terrains from Deep Seismic Profiling and Other Geophysical and Geological Investigations: A LEGENDS Initiative

We here argue the need for a multidisciplinary, integrated geophysical/geological survey across southern India and Sri Lanka, part of the largest exposed Neoproterozoic high-grade metamorphic terrain in the world. The purpose is to stimulate deep seismic profiling and other geophysical and geological investigations in order to better understand the structure, composition and evolution of a keystone of Precambrian continental crust and the role it played in the amalgamation and subsequent break-up of the Gondwana supercontinent. Of particular importance is that this lithospheric fragment records a 2 billion year long history of magmatism, sedimentation, deformation and metamorphism and now exposes at the surface rocks that once formed at depths of 30 km or more and that record unusually high metamorphic temperatures of up to 1000°C. Modern geophysical data should help to determine what lies underneath these high-T surface rocks and whether the terrain consists of structural distinct subunits separated by (now hidden) sutures. It is likely that the crustal-scale structures generated during the formation of the SGT may extend to other, now dispersed, segments of the Gondwana landmass and their identification in geophysical data will provide a fresh basis for reconstructing the process of supercontinent assemblage and break-up.     

综合物探技术在松山隧道勘察中的应用

松山隧道线路位于松山国家级自然保护区,勘察过程中不允许对植被造成大面积的破坏,且由于地形地貌的原因,采用传统勘察手段很难查明拟建隧道覆盖层的厚度、地层分界线以及不良地质体的分布情况,因此非常有必要开展先进的物探技术研究,探索一套适用于山区复杂地形条件下的、不破坏地表植被的绿色勘探技术。本文针对复杂地表和绿色勘探技术的需求,在松山隧道勘察中,针对不同位置、不同埋深,采用多种物探方法,结合地质资料进行综合分析,推断了隧道洞口位于碎石和块石中,开挖时应加强边坡加固措施;推断了里程K28+945~K29+100区间,隧道位于强风化基岩中,里程K30+645~K31+360区间内,隧道位于裂隙发育带,该两处开挖时应加强超前预报和支护工作。研究表明,本文提出的多种物探方法结合开展勘察的技术,是一套适用于山区复杂地形、不破坏地表植被的、有效的绿色勘查技术,在隧道勘察前期,应用该技术对隧道开挖区域进行勘查,可以提前掌握隧道开挖区域的地质情况,为隧道施工提供可靠依据,保障隧道施工顺利进行。     

利用正演模拟实现面波衰减

瑞雷波是分布在自由表面附近的P-SV面波,具有强振幅、低频、频散的特征,常用于工程物探,而在油气勘探及深部探测中常作为一种"干扰"波,会影响地震资料的信噪比,需要将面波净化处理。为实现面波衰减,本文将工程物探方法和石油物探技术相结合,通过面波频散曲线反演获得高精度的近地表模型,在三维近地表横波速度模型基础上进行面波正演,利用面波模型自适应匹配相减的方法将其减去,在不伤及有效波的情况下将面波的影响降至最低,一定程度上避免了常规面波衰减方法伤及有效波、损失低频弱信息、导致资料有效频带变窄、对地震构造解释及反演造成负面影响等缺点。最后应用实际数据验证了本研究方法的有效性。     

坝基卸荷回弹张裂面声波异常分析研究

在坝基施工过程中,利用声波测井方法确定坝基卸荷回弹张裂面应进行相对异常和地质物探趋势面分析研究,才能保证物探资料的可靠性及直接指导设计变更和施工组织.地质物探趋势面分析是作者的一种新提法.     

Multidisciplined investigation to locate the Kentucky shipwreck

A local artifact collector contacted the U.S. Army Engineer District, Vicksburg in the fall of 1994 concerning timbers from a ship protruding from the west bank of the Red River, Louisiana, during the summer of 1994. From historical records it was determined that the shipwreck is that of the Kentucky, which sank in 1865. An investigation integrating archaeological, geological, and geophysical methods was undertaken to determine the location, orientation, and depth of the wreckage. Based on site geology, the shipwreck is expected to lie within a silty sand deposit within 4–8.5 m below the ground surface. The results of probe investigations performed by the archaeologists and borehole data orient the long axis of the ship N57.5E. This orientation conflicts with the geophysical data, which suggest an orientation of N116W. The geophysical surveys identified an anomalous region, approximately 31 m long and 10 m wide, that borders the Red River and an abandoned channel of the Red River. The magnetometer data suggests that the bow of the ship is pointed toward the abandoned channel. This orientation contradicts historical records which have the bow pointing toward the modern Red River. A subsequent underwater investigation by the archaeological contractor discovered a rudder‐related mechanism protruding from the bank of the Red River, confirming the geophysical prediction. All three scientific surveys agree that the wreckage is at a depth 3.8–8.5 m below ground surface and at an inclined position, with a downward slope from the bank of the Red River to the abandoned channel. © 2000 John Wiley & Sons, Inc.*     

广东省潼湖生态智慧区浅层地球物理探测与地层物性分析

地质灾害、活动断裂、特殊岩土体和古河道等是影响城市浅层地下空间开发安全的主要地质问题,对于这些地质问题的探测主要采用地球物理无损检测方法。潼湖生态智慧区是国家生态文明建设示范区和惠州智慧城市地下空间开发中的重要区域,浅层地球物理探测与地层物性分析为潼湖生态智慧区城市发展及地下空间开发利用提供详细的地质、岩土和地球物理数据,是构建该地区地下空间模型的必备要素。虽然目前已经开展了针对本区域的基础地质探测研究工作,然而服务于精细地质结构与地层划分的综合地球物理研究还处于空白。针对浅层地下空间探测精细程度低和传统探测方法分辨率有限的问题,本文综合利用浅层反射波地震方法、混合源面波S波速度成像方法、三分量谐振波阻抗比值方法以及综合测井方法对该地区浅层地下空间(200m)进行了高精度地层划分和断层展布精细解释。在浅层地震反射波方法划分厚层和大尺度断层的基础上,利用主动源和被动源微脉动阵列法获得更加精细的浅层地层和构造特征,采用三分量地震频率谐振方法识别浅层土壤层分层,弥补了单一方法在不同深度范围上的探测信号低精度缺点,探讨了潼湖地区地层与地球物理的响应特征,构建了详实的地层物性和地球物理参数关系,为后续的建模提供基础数据。     

On the Solution of a Direct Problem for Determining the Parameters of Rayleigh-Type Waves in Layered Geophysical Medium

Doklady Earth Sciences - The patterns of propagation of elastic surface waves in a layered geophysical medium, which can be used in the search for buried inhomogeneities, are studied. Relationship...     

应用综合物探方法探测煤矿采空区

采煤活动造成的地下采空区会引发地表沉陷等严重的地质灾害,影响人们正常的生产和生活活动。根据煤矿采空区表现出来的地球物理特征,能够利用高密度电阻率法、瞬变电磁法、地震勘探、测氡法等物探方法探测其位置和范围。选择两种或两种以上的方法组合,可以实现优势互补,提高物探的解释精度。     

Geophysical identification of unmarked historic graves

Down‐hole magnetic susceptibility techniques were explored as a means of improving near‐surface geophysical surveys in historic grave detection. These techniques were used to document distinctive magnetic characteristics of grave shafts at three historic cemeteries first surveyed using various near‐surface geophysical methods. Tests revealed a low magnetic susceptibility signature that soil magnetic studies indicated was largely related to differential soil compaction associated with the excavation and refilling of grave shafts. Most apparent at depths beyond those reached by soil penetrometers, this magnetic signature offers a way to assess anomalies identified by near‐surface techniques that potentially represent graves. At one cemetery, magnetic studies of the interments themselves suggested spatially patterned, magnetically enhanced zones that might also aid in burial identification in certain contexts. While down‐hole techniques will not be foolproof, they do provide another geophysical tool that can be used to improve grave detection. © 2010 Wiley Periodicals, Inc.     

井～井超高密度电阻率法确定黑牛洞深部矿体的走向研究——以四川九龙县黑牛洞铜矿为例

超高密度电阻率法具有操作方便,快捷、适用性强、数据采集量大等特点。在黑牛洞里五铜矿实施进一步找矿勘探时,由于矿区地层复杂,地表地形变化大,矿体的空间走向变化也较大。通过钻探揭露的深部矿体在断面图上的连接形态有些不合理,而采用超高密度电阻率法做井～井物探探测后,对矿体空间连接的确定,起到了很好的指导作用。     

鄂尔多斯盆地寒武系-二叠系层序界面类型特征及油气地质意义

在鄂尔多斯盆地寒武系—二叠系地层中识别出不整合面、渣状层、古喀斯特作用面、冲刷侵蚀面、岩性与岩相转换面、超覆面、最大海泛面等层序界面。在详细讨论各类型界面特征的基础上,将其成因划分为构造运动造山侵蚀不整合界面、升隆侵蚀不整合界面、海侵上超层序不整合界面、暴露不整合界面4种类型。层序界面不仅是层序划分的关键,同时也具有重要的油气地质意义。层序界面是盆地盆地构造演化的物质响应,同时也是形成优质储集空间和油气运聚通道的重要地质条件。     

地球物理探测技术在成都市浅表地质结构调查中的应用研究

【研究目的】 查明城市浅表地质结构特征,对于城市地下空间规划、开发区建设、地质灾害评价等有着重要的指导意义,而无损、抗干扰能力强的地球物理探测技术在提供城市地区地下地质信息方面可以发挥关键作用。【研究方法】 为了支撑成都市浅表的三维地质填图工作,本文应用11种新、老地球物理探测技术,开展了成都市浅表地质结构的探测研究。【研究结果】 研究结果表明：（1）地质雷达对于近地表的地层结构成像、建筑结构识别分辨率较高;（2）瞬态面波、混合源面波、三分量频率谐振法对50 m以浅的地质结构识别能力强,分辨率很高,但探测深度有限;（3）微动勘探法和高密度电阻率法对50 m以浅的地质结构分辨率较高,但深部分辨率一般;（4）等值反磁通瞬变电磁抗干扰能力强,施工效率高,50 m以浅分辨率较高,50~200 m深度范围内分辨率一般,对膏岩泥岩有较好的识别能力;（5）半航空瞬变电磁可弥补了常规物探方法无法进入特殊场地施工的不足;（6）浅层地震勘探对于浅地表50～300 m深度范围内的砂泥岩互层的变化特征和断层结构特征效果较好,配合自然伽马曲线,可有效识别砂泥岩的岩性界面;（7）音频大地电磁可有效识别成都平原深大断裂的空间分布形态。【结论】 综合各种地球物理方法的优缺点,建立了成都市浅表地质结构的地球物理组合探测技术方案,以期能为今后的城市浅表地质结构调查提供参考。     

高放废物地质处置阿拉善预选区巴彦诺日公地段目标深度岩体质量预测

高放废物地质处置阿拉善预选区巴彦诺日公地段位于阿拉善地块东部,主要由二叠纪侵入的花岗岩构成,地壳次稳定。通过踏勘,确定了2个钻孔,布置了若干条物探剖面。以这2个钻孔为中心,在17km×17km范围内进行了工程地质测绘,获得了地表结构面分布特征。地表岩体质量以III级岩体为主,地表以下3m~4m处多为I级和II级岩体。根据钻孔岩芯编录和力学试验数据,对岩芯质量进行评价,岩芯整体质量较好,以Ⅰ级和Ⅱ级岩体为主。对比岩体质量和测井数据,发现岩体质量与岩体的物理参数具有明显的相关性。通过和CSAMT剖面上对应位置的对比,建立了岩体质量与电阻率的关系。结合地表岩体质量、钻孔岩芯质量和物探剖面,对目标深度岩体进行了预测：目标深度（600m深左右）岩体质量以Ⅰ级岩体为主,局部有Ⅱ级岩体和Ⅲ岩体。