综合物探方法在石膏矿采空区探测中的应用研究

为探讨综合物探方法在石膏矿采空区探测应用的适宜性和局限性,本文以荆门市石膏矿采空区为研究对象,选用高密度电法、激电中梯法以及地震映射法等综合物探方法开展石膏矿采空区探测工作,辅以钻探工作加以验证,对以上三种物探方法在石膏矿采空区探测的适用性和优缺点进行了对比分析.分析结果表明:高密度电法高效便捷,但其精度有限,可以用于圈定采空区的大致分布和范围;激电中梯法能简单直观地查明采空区充水现状,其勘查结果对石膏矿采空区稳定性分析及发展趋势预测十分重要;地震映射法精度高,探测效果好,可用于石膏矿采空区治理靶区的详细勘查,但其工作效率低,且无法查清采空区的充水特征.综上可知,在石膏矿采空区勘查实际应用中,应根据不同的地质条件以及勘查目的,合理选用物探方法组合及试验参数,对各方法的成果要相互验证,取长补短,才能有效提高勘查成果准确性和可靠性.     

采空区地震与电法探测数据的联合反演研究及应用

综合地球物理技术在采空区的探测中发挥了重要作用.目前通常采用单方法反演、仅对不同方法反演结果进行对比解释的综合勘探方式,单方法反演的多解性严重降低了其探测精度.如何提高采空区的探测精度,对采空区进行有效探测一直被认为是地球物理技术面临的首要难题.为了提高地震与电法技术的探测精度,基于交叉梯度联合反演理论,设计了地震初至折射走时数据和高密度电法数据的联合反演算法流程,对采空区理论模型和野外实际数据进行了联合反演处理.结果发现通过两者的联合反演,不仅可以提高采空区电阻率反演模型的成像效果,而且能够获得地震单方法反演难以成像的采空区低速异常体,从而提高了地震与电法技术对采空区的探测精度.表明地震与电法探测数据联合反演是一种提高采空区探测精度的有效方法.     

S变换数据重构地震映像在六威线六盘水车站煤窑采空区勘探中的应用

地震映像对现场施测条件的要求较低,非常适合小煤窑采空区的勘探,应用前景十分广泛.传统的地震映像方法通常通过观察岩溶附近绕射波的方法来识别,但常常受制于噪声的影响,探测效果不佳,制约了该项技术的发展.本文提出在选择最佳偏移距,最佳频段的基础上,将地震映像资料经S变换数据重构至频率域,以地震波频率衰减的强弱作为识别物探异常区域的标志,并将其应用至六威线六盘水车站煤窑采空区铁路工程物探中,经过与同测线超高密度电法资料对比,物探异常分布基本一致,且与钻孔验证吻合.通过对地震映像法资料进行S变换等特殊处理,为小煤窑采空区物探技术发展提供了一种新思路.     

高频电磁测深法在钼矿采空区探测中的应用

采空区给人类生产生活带来危害,采空区的探测已成为重要研究课题.针对采空区的特点,合理选择物探方法、灵活运用物探方法是准确探测采空区的关键.本文介绍了高频电磁测深法的原理、特点和工作方法,通过分析已知采空区与未知采空区的测量结果,说明高频大地电磁测深是探测采空区的有效手段.通过某钼矿采空区探测中的实例,验证了此方法在钼矿...     

采空区勘查新技术及应用

采空区危害巨大,但常用物探方法往往难以准确探测.为了寻找适合的采空区探测物探方法,本文介绍了基于散射地震理论的SSP地震散射技术的原理和技术要点,SSP技术以非均匀地质模型为基础,适应复杂地质、地形条件;通过波场分离、速度分析、偏移成像技术,可得到地层的波速分布与地质界面分布图像.同时本文结合实例研究了SSP技术在采空区勘查中的应用效果.结果表明:相比于反射地震方法将时间同相轴形态变化作为判定采空区标准,SSP技术依据低速区分布判定采空区的方式更加直观、准确;并结合界面形态综合解释采空区,进一步提高了勘探的准确度;该方法具有分辨率高、探测深度大等特点;在应用中取得了令人满意的结果.     

浅层铝土矿采空区探测及引发的地面沉降预测

以山东省淄博市某浅层铝土矿采空沉陷灾害为例,采用高密度电阻率和探地雷达技术调查采空区尺寸、范围及充填情况.然后根据探测结果构建相应地质模型,基于Biot固结理论采用有限元法预测采空区上部土层沉降量,对可能发生的沉陷灾害进行预警.研究结果显示两种物探方法相互验证,可准确确定采空区上部土层微结构、采空区边界及充填情况.对于顶部塌陷的小型采空区,沉降量计算可参考荷载作用下的土体固结过程.研究建立了一类无序开采的小型采空区探测及灾害预测方法,突出了高精度物探技术在小型采空区地质灾害调查中的重要作用.     

关闭小煤矿采空区地面探测方法优选

本文在关闭小煤矿采空区探测应用实例的基础上,依据地质条件的差异性和探测方法自身的局限性,选定三维地震、瞬变电磁和测氡法等3种技术进行了优选研究.结果表明,整体上三维地震能够给出采空区的空间分布,探测精度、可靠性最高,其施工成本高、工艺复杂、工期长,整体探测效率较低;测氡法能够定性圈定采空区及巷道分布区,探测精度、可靠性...     

用于深部采空区探测的可控源音频大地电磁法抗强干扰数据采集及处理策略

高速公路施工穿越煤矿采空区,存在巨大的安全隐患,严重威胁人员和道路安全,因此准确探测煤层采空区位置对公路勘察具有重要的现实意义.本研究采用可控源音频大地电磁法(Controlled-Source Audiomagnetotellurics,简称CSAMT)对煤矿采空区进行探测.为提高强干扰背景下深部采空区的探测精度,本研究有针对性地采取了相关数据采集及处理策略.首先结合采空区地质地球物理特征,在强干扰背景下进行多次试验工作,重点研究发射频率、发射电流、发射距等对高精度数据采集的影响,以确定最佳的组合采集参数.然后,在数据处理过程中着重探讨静态效应对反演结果的影响,同时对反演后的结果采用阈值分割方法突出深部采空区电性异常特征.最后结合研究区已有地质物探资料与反演获取的各测量剖面电阻率断面图,查明隐伏采空区的位置、分布范围、规模等基本情况,并布设钻井进行验证,结果表明,实际采空区的埋深及位置与物探异常对应较吻合,验证了本方法的可行性与有效性.     

人工挖孔桩桩底探测方法与应用

在石灰岩地区的建筑基础设计为挖孔桩时,需进行桩底岩溶探测。本文介绍了3种可行的桩底探测方法,主要对地质雷达法与地震反射波法两种物探方法的基本原理及具体探测技术进行了介绍,通过对物探方法与传统钻探法进行有效组合可以提高人工挖孔桩桩底探测的效率和准确性。     

综合物探方法在铁矿采空区探测中的应用研究

针对铁矿采空区的特点,合理选择物探方法、灵活运用物探方法是准确探测采空区的关键。根据铁矿开采前后磁场的变化特征,结合开采前的物探资料,利用高精度磁测探查采空区的空间分布、埋深是一种新的尝试,同时结合其它物探方法可相互补充、相互印正,效果更好。通过实例介绍了综合物探方法在铁矿采空区探测中的应用效果。     

电阻率层析成像法在辽阳活断层探测中的应用

电阻率层析成像法是近年来迅速发展起来的地球物理新技术,目前逐渐成为工程物探中的主要方法。在辽阳市地震活断层与地震危险性评价研究中运用该方法取得了良好的效果。通过在目标区布设探测剖面,辅以浅层地震,地质钻探,可以准确地探测断层的几何结构和物理特征,为辽阳市活断层探测与地震危险性评价研究提供准确可靠的物探依据。     

多道瞬态瑞雷波技术在公路采空塌陷区探测中应用

地下采空塌陷区岩体结构具有明显的结构不连续、松散、断裂、空洞等异常结构特征,本文在分析公路采空塌陷区地球物理场特征的基础上,详细讨论了应用多道瞬态瑞雷波技术探测采空塌陷区的可行性以及相关技术,深入分析基于瑞雷波波场特征、频谱结构、能量衰减、频散特征、相速度以及多阶模等特征探测和评价地层结构的均匀性、地下空洞及异常结构体等地下障碍物的存在及其空间分布的解释标志.滚动式多道瑞雷波探测技术可以有效地探测地下采空区、软弱结构体等异常结构体的赋存状态及空间分布.     

闽西南多金属成矿带地质地球物理特征综合研究——以永定大排多金属矿区为例

闽西南地区位于福建武夷山成矿带西南部,自远古宙以来经历了多期次的构造演化.该区地处东南沿海构造-岩浆-成矿带上,为环太平洋大陆边缘多金属成矿带与南岭多金属成矿带复合部位,是我国重要的多金属矿产地.永定大排多金属矿区作为近年来武夷山成矿带新发现的大型多金属矿,区内叠加作用和控矿作用相对复杂,现有的地质地球物理工作程度不足以满足对该区域成矿规律的深入认识,一些基础地质问题亟待解决.因此,本文在深入收集永定大排矿区地质地球物理资料基础上,综合分析区域成矿背景与成矿构造,在重点区域布设综合地球物理勘探工作,包括1：1万高精度磁测、可控源音频大地电磁剖面及反射地震剖面.基于上述工作：1）开展了研究区航磁数据三维磁化率反演与分布特征分析与大地电磁二维电阻率反演与分布特征分析,开展了地震资料真地表深度偏移成像,获得了更加准确的地震剖面成像结果.2）结合推覆体控矿特征,地震剖面和电阻率剖面、航磁反演结果相互验证和约束,勾画了地下构造形态.地表地质剖面延伸和标定了构造形态的地质内涵,获得了从地表到3000 m深度的构造解释结果.解释结果清晰地显示了与推覆相关的构造、控矿层位以及岩体信息,为三位一体的找矿思路提供了地球物理依据.     

技术应用综合物探方法在张家口某工程场地地震安全性评价中的应用研究

结合地质和遥感图像解译资料,以物探方法查找活断层是行之有效的方法。针对单一的物探方法在反演解释中具有多解性的弊端,本文提出以高密度电阻率法为主,浅层地震反射波法为辅的综合物探勘察组合模式。经实际钻探证明,这种综合物探模式对隐伏活断层的勘察是完全可行的,并具有较强的实用推广性。     

Electrical resistivity and seismic refraction tomography to detect buried cavities

Near‐surface cavities can pose serious hazards to human safety, especially in highly urbanized town centres. The location of subsurface voids, the estimation of their size and the evaluation of the overburden thickness are necessary to assess the risk of collapse. In this study, electrical resistivity tomography (ERT) and seismic refraction tomography data are integrated in a joint interpretation process for cavity location in the city of Rome. ERT is a well established and widely employed method for cavity detection. However, additional information provided by seismic refraction tomography is capable of eliminating some potential pitfalls in resistivity data interpretation. We propose that the structure of the cavities defined by ERT can be used as a base to optimize seismic refraction tomography investigations within the framework of a joint interpretation process. Data integration and the insertion of a priori information are key issues for reducing the uncertainties associated with the inversion process and for optimizing both acquisition procedures and computation time. Herein, the two geophysical methods are tested on both synthetic and real data and the integration of the results is found to be successful in detecting isolated cavities and in assessing their geometrical characteristics. The cavity location inferred by geophysical non‐invasive methods has been subsequently confirmed by direct inspection.     

Integrated geophysical and chemical study of saline water intrusion

Surface geophysical surveys provide an effective way to image the subsurface and the ground water zone without a large number of observation wells. DC resistivity sounding generally identifies the subsurface formations-the aquifer zone as well as the formations saturated with saline/brackish water. However, the method has serious ambiguities in distinguishing the geological formations of similar resistivities such as saline sand and saline clay, or water quality such as fresh or saline, in a low resistivity formation. In order to minimize the ambiguity and ascertain the efficacy of data integration techniques in ground water and saline contamination studies, a combined geophysical survey and periodic chemical analysis of ground water were carried out employing DC resistivity profiling, resistivity sounding, and shallow seismic refraction methods. By constraining resistivity interpretation with inputs from seismic refraction and chemical analysis, the data integration study proved to be a powerful method for identification of the subsurface formations, ground water zones, the subsurface saline/brackish water zones, and the probable mode and cause of saline water intrusion in an inland aquifer. A case study presented here illustrates these principles. Resistivity sounding alone had earlier failed to identify the different formations in the saline environment. Data integration and resistivity interpretation constrained by water quality analysis led to a new concept of minimum resistivity for ground water-bearing zones, which is the optimum value of resistivity of a subsurface formation in an area below which ground water contained in it is saline/brackish and unsuitable for drinking.     

高密度电法在水库坝址区勘察中的应用

近年来高密度电法被广泛应用于重大水利工程场地的工程地质调查、坝基及桥墩选址、采空区及地裂缝探测等诸多工程勘察领域。本文利用高密度电法对某水库大坝坝址区的覆盖层厚度、隐伏断层等地质结构进行探测,并在结合钻探资料和区域地质资料综合分析的基础上,取得了理想的勘察结果。查明水库区存在隐伏的断层和覆盖层厚度,为水库坝址选择提供重要的地球物理依据。      

Potential Field,Geoelectrical and Reflection Seismic Investigations for Massive Sulphide Exploration in the Skellefte Mining District,Northern Sweden

Multi-scale geophysical studies were conducted in the central Skellefte district (CSD) in order to delineate the geometry of the upper crust (down to maximum ～ 4.5 km depth) for prospecting volcanic massive sulphide (VMS) mineralization. These geophysical investigations include potential field, resistivity/induced polarization (IP), reflection seismic and magnetotelluric (MT) data which were collected between 2009 and 2010. The interpretations were divided in two scales: (i) shallow (～ 1.5 km) and (ii) deep (～4.5 km). Physical properties of the rocks, including density, magnetic susceptibility, resistivity and chargeability, were also used to improve interpretations. The study result delineates the geometry of the upper crust in the CSD and new models were suggested based on new and joint geophysical interpretation which can benefit VMS prospecting in the area. The result also indicates that a strongly conductive zone detected by resistivity/IP data may have been missed using other geophysical data.     

Tectonic activity and earthquake risk in the Cheng-nanhe fault zone in Weihai city,Shandong province,China, obtained by using an integrated prospecting technique in geophysics and geology

For city planning and reducing potential earthquake risk, it's necessary to detect the information of the buried faults in an urban area especially, including the location and activities. An integrated technique with geophysical and geological methods, including the shallow seismic reflection profile, electrical resistivity measurement, geologic borehole section, and exploration trench, was used to detect the Chengnanhe fault, which is one of the two main faults passing through the Weihai urban area in Shandong province, China. The results show that it is a normal fault striking with E-W direction, and it is relatively inactive and stable. By using the thermoluminescence (TL) dating, we found that the Chengnanhe fault initiated in mid-Pleistocene and there was no offset after late Pleistocene. Such an integrated technique with multiple geological and geophysical methods provides a significant assessment of earthquake risk for city planning in urban areas.