共查询到16条相似文献，搜索用时 203 毫秒
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土石坝渗漏问题是制约水库大坝安全运行的重要隐患,准确查明大坝渗漏的病因以及靶区的空间展布是有的放矢实施加固的关键.针对土石坝隐患的空间位置信息多变、周围介质复杂等难点,单一探测手段在识别病灶方面存在误判、漏判等问题,考虑到电阻率对水敏感的特点,提出联合并行电法和瞬变电磁法优化诊断土石坝渗漏隐患的思路.为查明戴家坞水库渗漏的病灶,利用并行电法快速获得大坝坝体段不同高程下的二维视电阻率图像,分析比较了AMN、MNB以及AMN&MNB装置的反演结果,还采用瞬变电磁法对大坝两坝肩并行电法盲区部位进行补充探测,并依据成果进行防渗处理.试验结果表明,并行电法有效指示出大坝坝体段的渗流异常,综合多剖面异常信息能追踪到渗漏路径;AMN&MNB装置的反演结果有效吸收了AMN、MNB的局部高分辨的优势,对大坝边界以及隐患规模的细节刻画更清晰;结合二次场响应曲线和视电阻率图像,瞬变电磁法很好揭示出大坝坝肩K0-005～0+002 m段的渗漏通道,同时有效规避了硬化路面电极接触不良的难题.经对综合推断隐患区进行灌浆处理,大坝渗漏量明显降低,从而佐证了两种方法优化联合的可行性.研究成果可为水库大坝隐患的全面、精细探查提供技术支撑. 相似文献
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无基坑振冲加密施工是一种比较先进的土石坝建筑方法。以海南省三亚市西部的宁远河中下游河段的大隆水利枢纽工程土石坝为研究对象,对其进行准确分区,以饱和-非饱和渗流理论为基础,通过三维有限元数值方法,模拟库水下降作用下的土石坝渗流场,并对各级水位下的孔压、流速及流向进行分析,评价大坝的渗流安全。研究结果表明：采用无基坑振冲加密施工方法后,坝体内填砂砾振冲层形成上游排水通道,在坝前水位骤降工况下,防渗土料内有效流速方向和渗透压力的方向由近水平的指向坝面变为竖直向下指向填砂砾振冲层,而且有效流速明显变大,利于渗透水通过填砂砾振冲层排到下游,有利于上游坝体稳定。 相似文献
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地面磁共振探测(Surface Magnetic Resonance Sounding,SMRS)是近年来发展起来的一种地球物理新方法,这种在地面直接探测地下介质中氢核丰度的技术,不仅可以用于缺水地区的地下水资源勘查与评价,还可以在地下水引起的堤坝渗漏、滑坡、海水入侵等地质灾害水源的探测预警中发挥独特的作用.本文首次提出了地下磁共振探测方法(Underground Magnetic Resonance Sounding,UMRS),将SMRS方法引入到地下工程领域,实现隧道工程和煤矿开采等地下狭窄空间极端环境的探测.为应用UMRS方法,需要深入研究地下水超前探测理论、准全空间处理与反演方法、旋转多匝小线圈探测模式,强电磁干扰环境自适应噪声压制策略、以及复杂地质环境磁共振与瞬变电磁联合探测关键技术等难题.论文还简要介绍了超导磁探测技术和工程盾构及掘进实时探测等新技术在地下工程生产安全探测预警中的应用前景. 相似文献
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近20多年来,用核磁共振(Nuclear Magnetic Resonance,NMR)方法形成的一种直接非侵害性的探测地下水的地球物理新技术,与传统的地球物理探测地下水的方法相比具有高分辨力、高效率、信息量丰富和解的唯一性等优点,是一种很有发展前景的找水方法技术.我国的水资源短缺,对地下水资源的勘探、开发与利用十分重视,已将核磁共振找水技术研究列入国家十一五科技支撑计划.本文在广泛收集迄今为止的国内外大量资料的基础上,并根据作者近年来有关核磁共振找水技术的研究经历,综述了核磁共振找水技术的发展历史、现状和发展趋势,以推进我国核磁共振找水技术的发展. 相似文献
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核磁共振测深方法的新进展 总被引：4，自引：1，他引：3
核磁共振测深(MRS)方法是目前唯一直接探查地下水的新方法.本文概要介绍了参加第二届核磁共振测深(MRS)国际学术研讨会的主要收获.阐述了核磁共振找水仪的研制和进展以及扩大了MRS方法的应用领域方面的情况.在应用MRS方法探测地下水取得很大成效的此基础上,我们率先用MRS方法进行了三峡滑坡监测和秦始皇陵考古工作,又取得了新成果. 相似文献
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地面核磁共振方法是目前唯一直接探测地下水的地球物理新方法。新方法在我国探查地下水等方面已取得明显的效果,但是,对于SNMR信号,却有很多影响因素。本文论述并分析了诸多影响因素中的地磁场强度和磁倾角对NMR信号的影响特点,进而分析了我国区域地磁场强度和磁倾角对SNIVIR信号的影响规律,对我国进行区域性水文地质调查中运用SNMR方法时提供了重要的参考资料。 相似文献
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目的 医学核磁共振与地面核磁共振找水是核磁共振技术应用的不同领域。本文通过对二者在方法原理、技术、应用等方面的对比研究，提出了地面核磁共振找水工作建议。 相似文献
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Inversion of resistivity in Magnetic Resonance Sounding 总被引：3，自引：0，他引：3
Magnetic Resonance Sounding (MRS, or Surface Nuclear Magnetic Resonance - SNMR) is used for groundwater exploration and aquifer characterization. Since this is an electromagnetic method, the excitation magnetic field depends on the resistivity of the subsurface. Therefore, the resistivity has to be taken into account in the inversion: either as a priori information or as an inversion parameter during the inversion process, as introduced in the presented paper. Studies with synthetic data show that water content and resistivity can be resolved for a low resistive aquifer even using only the amplitude of the MRS signal. However, the inversion result can be significantly improved using amplitude and phase of the MRS signal. The successful implementation of the inversion for field data shows that the resistivities derived from MRS are comparable to those from conventional geoelectric methods such as DC resistivity and transient electromagnetic. By having information about both the resistivity and the water content, MRS inversions give information about the quality of the water in the aquifer. This is of utmost interest in hydrogeological studies as this specific information cannot be determined solely by geoelectric measurements, due to the nonunique dependence of resistivity on water content and salinity. 相似文献
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综合物探技术在堤坝隐患探测中的应用 总被引：17，自引：8，他引：9
本文给出笔者参与的浙江温岭东浦新塘隐患探测、椒江外沙海塘渗漏探测、缙云白马水库和玉环里墩水库坝体渗漏探测等几个实例,详细说明了综合物探技术在堤坝隐患探测中的作用、优点和需要注意的问题,具体分析了堤坝隐患的不同特征和综合物探方法的特点.工作实践表明：高密度电阻率法、探地雷达法、瑞雷波法及其综合运用能有效探测坝体缺陷,查明渗漏原因.同时,由于每种方法各有应用前提及局限性,故应针对可能的隐患特征,选用合适的探测方法及其组合,并努力提高信号采集和处理解释水平. 相似文献
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Resistivity and self‐potential tomography can be used to investigate anomalous seepage inside heterogeneous earthen dams. The self‐potential (SP) signals provide a unique signature to groundwater flow because the source current density responsible for the SP signals is proportional to the Darcy velocity. The distribution of the SP signals is also influenced by the distribution of the resistivity; therefore, resistivity and SP need to be used in concert to elucidate groundwater flow pathways. In this study, a survey is conducted at a small earthen dam in Colorado where anomalous seepage is observed on the downstream face at the dam toe. The data reveal SP and direct current resistivity anomalies that are used to delineate three anomalous seepage zones within the dam and to estimate the source of the localized seepage discharge. The SP data are inverted in two dimensions using the resistivity distribution to determine the distribution of the Darcy velocity responsible for the observed seepage. The inverted Darcy velocity agrees with an estimation of the Darcy velocity from the hydraulic conductivity obtained from a slug test and the observed head gradient. 相似文献
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The surface nuclear magnetic resonance (SNMR) method has been tested at a site in Haldensleben, northern Germany, to assess the suitability of this new method for groundwater exploration and environmental investigations. More information is obtained by SNMR, particularly with respect to aquifer parameters, than with other geophysical techniques. SNMR measurements were carried out at three borehole locations, together with 2D and 1D direct current geoelectrics, as well as ground-penetrating radar, and well logging (induction log, gamma-ray log and pulsed neutron-gamma log). Permeabilities were calculated from the grain-size distributions of core material determined in the laboratory. It is demonstrated that the SNMR method is able to detect groundwater and the results are in good agreement with other geophysical and hydrogeological data. Using the SNMR method, the water content of the unsaturated and saturated zones (i.e. porosity of an aquifer) can be reliably determined. This information and resistivity data permit in situ determination of other aquifer parameters. Comparison of the SNMR results with borehole data clearly shows that the water content determined by SNMR is the free or mobile water in the pores. The permeabilities estimated from the SNMR decay times are similar to those derived from sieve analysis of core material. Thus, the combination of SNMR with geoelectric methods promises to be a powerful tool for studying aquifer properties. 相似文献
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地面磁共振是一种新的地球物理探测方法,能够通过探测地下水中氢质子丰度获取地下水含量、孔隙度等水文地质信息.然而,磁共振信号甚为微弱,仅达到纳伏级(10~(-9)V),极易受到噪声干扰.其中,尖峰噪声对磁共振信号影响最为严重,亟待研究有效的噪声抑制方法.小波多尺度分解硬阈值是近两年国际磁共振领域专家提出的尖峰噪声有效消除方法,但硬阈值算法设定阈值的固有缺陷会引发信号震荡,出现伪吉布斯效应,导致信号损失.基于此,本文提出压缩小波变换(Synchrosqueezing Wavelet Transform,SWT)和非线性國值处理(Nonlinear Thresholding,NT)算法联合消除磁共振信号尖峰噪声干扰.首先选择Morlet小波作为基小波,使得信号与噪声数据具有更高的时频集中性,利于尖峰噪声消除.其次,基于压缩小波系数进行非线性处理,可以弥补利用硬阈值和软阈值进行噪声消除时所引起的信号损失.仿真数据和实际数据结果表明,SWT联合NT方法可以利用单次采集数据有效消除尖峰噪声干扰并还原信号.本文提出的消噪方法将为磁共振数据后续反演解释,如多指数弛豫反演,奠定坚实的基础. 相似文献