岩溶裂隙水与不良地质情况超前预报研究

在岩溶地区隧道施工过程中,经常遇到突水、突泥等无法预料的地质灾害,给施工安全带来了重大灾难和无法估计的经济损失。为了保证岩溶隧道施工安全,对岩溶裂隙水与不良地质体的发育情况进行准确及时的超前预报,是当前岩溶地区隧道设计与施工中亟待研究与解决的关键问题。首先,对隧道建设过程中岩溶裂隙水与不良地质情况超前预报和综合预报体系的研究现状进行详细的介绍,指出岩溶裂隙水与不良地质情况超前预报中存在的主要问题,总结隧道建设过程中地质缺陷超前勘探方法和高压大流量岩溶裂隙水超前预报方法;然后,重点介绍TSP超前地质预报系统探测溶洞、陆地声纳法探测断层、地质雷达探测地下水和红外探水法探测岩溶裂隙水等工程实例。最后,总结预报各种不同地质体的有效方法和将要开展的研究热点和难点,并对下一步所要开展的工作进行深入探讨,对我国在岩溶裂隙水和不良地质体探查的理论和技术创新方面给予一定的帮助和指导。     

浅谈岩溶地区隧道施工中的岩溶处理

简要介绍了岩溶的成因，并结合工程实例论述了在隧道开挖施工中对不同的岩溶形态进行处理所采取的措施，结果表明，采用地质分析、钻孔勘探和地质雷达探测相结合是进行地质预测预报的有效手段，加强临时支护是穿越岩溶的安全保证措施。     

地质雷达在隧道超前预报中的应用

通过对地质雷达的工作原理、测试方法和图像判读的介绍,结合SIR-20地质雷达探测的工程实例,说明采用地质雷达探测掌子面前方的岩溶情况是可行的,对隧道施工具有一定的现实意义。     

地质雷达点测法在桥梁桩基岩溶检测中的应用

为了避免岩溶发育诱发的地质灾害对于桥梁桩基工程的安全施工和运行所造成的危害,通过介绍地质雷达检测的原理、方法及检测过程中相关参数的选择,并结合实际工程,利用地质雷达点测法,研究了桥梁桩基下岩溶发育引起的溶洞的位置及规模,对所测地质雷达图像进行了分析解释。研究结果表明：地质雷达探测技术可以有效地查明桥梁桩基底部岩溶发育的位置及规模,为制定治理方案提供了重要参考依据。     

综合超前地质预报技术在摩围山隧道的应用

摩围山隧道为地质条件复杂的岩溶隧道,所处地段岩溶发育、富含地下水及裂隙水、断层破碎带多。施工过程中采用了包括地面调查和隧道地质素描、TSP203、地质雷达及超前长、短探孔多种方法相互印证、相互补充的综合地质预报技术。对类似工程的超前地质预报提供有意义的参考和借鉴。     

齐岳山隧道岩溶裂隙水超前预报与治理研究

岩溶隧道灾害预报与治理是隧道快速安全施工的重要技术保障,以沪蓉西高速公路齐岳山隧道为工程背景,通过地质调查和分析,研究了隧址区岩溶发育规律,利用TSP地震波探测方法,对YK329 285～YK329 237高风险岩溶发育段进行了预报,基本探明了掌子面前方岩溶发育和含水情况,为及时制定处理预案提供了科学依据.针对该段开挖揭露后岩溶裂隙水的涌水情况,在准确探测出岩溶裂隙水的基础上,采用复合注浆技术,进行了岩溶水的注浆封堵.     

路基下隐伏溶洞探测技术应用研究

路基下隐伏岩溶病害严重地影响了道路行驶的安全,快速、连续、高效地进行路基病害探测和做好防治工作是铁路工程中的首要问题,以地质理论分析为基础,采用先进的地质雷达探测手段探测路基下隐伏岩溶大小和分布规律是一种十分有效的方法。结合路基下隐伏岩溶工程探测实例,分析了岩溶的形成规律和电磁波反射特征,提出了路基下隐伏岩溶探测的建议和措施,对进一步做好路基病害探测和防治工作具有重要的工程应用价值。     

高速公路岩溶地基稳定性分析

岩溶产生和病害受到多种因素影响,在对及产生和病害分析的基础上,介绍了岩溶地质探查中的地质雷达探测基本原理,并列出了探测方案中的主要内容,研究了岩溶地区路基稳定性相关因素,最后提出了工程处理的主要要点。     

综合物探方法在惠州新材料产业园岩溶探测中的应用

广东省惠州新材料产业园规划选址位于隐伏岩溶地区。为了查清产业园岩溶发育规律,笔者开展了综合物探工作,对惠州新材料产业园进行了专项岩溶探测。本文在介绍综合物探探测岩溶的方法与技术的基础上,合理选择高密度电阻率法、地震反射法、地质雷达法相关工作参数,确定数据处理与资料解释方法,最后通过物探成果分析与钻探验证,归纳总结了综合物探探测岩溶的经验与教训,研究成果可为隐伏岩溶地区的物探工作提供有益的参考和借鉴。     

高密度电阻率法在厚覆盖层隐伏岩溶隧道施工风险预判中的应用

在厚覆盖层岩溶发育区,采用高密度电阻率法、地质雷达法和超前水平钻探进行探测可较为准确查明岩溶发育的位置、规模、充填特征等。以贵州某岩溶隧道为例,利用高密度电阻率法查明了岩溶强发育区及与隧道的交叉关系,查明了隧道顶板上部岩溶的发育位置、规模、充填特征,较为准确的修正了隧道施工安全风险等级,通过地质雷达探测及在隧道开挖面周边合理布置一定角度的超前水平钻探,能够进一步查明岩溶发育特征及边界范围,进一步确定施工安全风险等级,为岩溶处置设计和施工提供了地质参考。     

Perturbation mapping of water leak in buried water pipes via laboratory validation experiments with high-frequency ground penetrating radar (GPR)

This paper studies the perturbation patterns of GPR images as a tool for water leakage detection in buried water pipes with laboratory experiments. Different perturbations patterns on GPR signals due to a water leak of metallic and PVC pipes buried in a sand box, were mapped and studied with controlled water injection and leak volume, as well as a fixed leak position in the pipes. These perturbation patterns of signal strength include the tale-tell signs of a central leak point and propagation of the radial wetting front vortex centered around the leak point at different injection times. These patterns, compared to the no-leak dry condition, were interpreted with the conventional principles of dielectric contrast and reflection coefficients, and the associated reflection and absorption mechanisms. It is believed that this set of data will serve as an image matching fingerprint to identify and map water leaks in the field.     

路用探地雷达的工程应用

路面结构层厚度检测是道路质量控制的重要工作,采用具有快速、无损、可连续测试的探地雷达技术对其进行检测,更能为竣工验收提供科学依据。文中介绍了探地雷达技术在公路路面工程厚度检测中的实际应用,说明探地雷达检测公路路面厚度在实际应用中是切实可行的,在公路工程质量检测中具有独特的优势,为公路路面厚度检测增添了一种新的技术方法。     

GPR在FAST馈源支撑塔地基探测中的应用

国家重大科学项目500m大射电望远镜(简称FAST)选址贵州平塘,台址地质构造复杂,工程地质条件较差,根据FAST结构的要求,其建在直径为600m圆周上的六个馈源支撑塔基为主要承重部位,为有效地评价塔基的稳定性,治理工程地质病害,本文以地质雷达在FAST馈源支撑塔地基探测为实例,分析了地质雷达技术在这种地形条件较差的环境中应用的可行性,在探测结果与开挖验证的精度对比分析中,总结得出在工程范围较大时,应分区进行现场物性试验,得到更精确的介质相对介电常数,从而提高探测解释的精度,说明了物探技术在岩溶地基探测中发挥的重要作用。随着物探方法研究的不断深入和雷达天线及信号处理技术的迅速发展,GPR技术将能更广泛地服务于工程建设领域,特别是国家重大项目。     

地质雷达在公路隧道超前地质预报中的应用

以松建高速慈口隧道为例,通过对地质雷达扫描图像的具体分析,对隧道实际开挖进行现场跟踪,并对设计、预报成果和实际揭露资料进行对比,表明地质雷达是隧道施工中对断层、富水区的一种较好的超前地质预报方法。     

Experimental monitoring of chloride-induced reinforcement corrosion and chloride contamination in concrete with ground-penetrating radar

In this article, we present a laboratory experiment to monitor the accelerated corrosion in concrete using ground-penetrating radar (GPR). Four concrete test specimens were cast with rebars of different size and placed at different depths. The lifetime decades of reinforcement corrosion process were accelerated into 18 days by using the impress current technique. The electrochemical corrosion process was periodically monitored with GPR. Two control specimens were also prepared to investigate the influence of chloride contamination on GPR signal. The measured data were analysed both in time and frequency domains. In time domain, the peak-to-peak amplitude of a wave reflected by a rebar was calculated to investigate the relationship between an increase in signal amplitude and the degree of corrosion. In frequency domain, the time–frequency representations of the signal were computed by using S-transform. The results show that reinforce corrosion increased the amplitude of reflected signal in time domain but did not change the peak frequency in frequency domain while chloride contamination attenuates the signal to smaller amplitude and lower peak frequency. Based on the results, a novel process is finally proposed for GPR-based corrosion detection.     

Identifying voids in plastic ducts in post-tensioning prestressed concrete members by resonant frequency of impact–echo,SIBIE and tomography

A series of standard concrete beams with plastic P-T tendon ducts were tested at the University of Edinburgh using a range of NDT techniques including impact–echo (I–E), stack imaging of spectral amplitudes based on the impact–echo (SIBIE) and ultrasonic tomography. The findings were confirmed by comparison with earlier experiments undertaken using GPR. It has been argued that I–E cannot detect voids in plastic post-tensioned ducts readily. However it has been shown that whilst I–E is less effective on plastic ducts, the SIBIE analysis is more certain. This technique is easier to use than ultrasonic tomography and gives a credible evaluation. The paper goes on to analyse the above tests on a number of beams with confirmation for ultrasonic tomography and GPR.     

A mobile android tool for simplified GPR data processing in construction applications

This work presents a new GPR signal processing tool for mobile devices, which uses the free Android platform in smartphones and tablets. The developed application is able to display and process radargrams without using the most common commercial software applied for GPR signal processing. These existing applications have usually been developed for advanced signal processing, which results in complex processes and requires large computational resources. Therefore, the aim of this work was to develop a simplified and intuitive tool, which allows speeding up the GPR signal processing. For such purpose, the application implements basic filters to optimize the GPR images analysis and to facilitate data interpretation. Different tools have also been implemented to obtain interesting geometric measurements, such as thicknesses and diameters in rebar or piping. Thus, any non-expert user on the GPR technique could generate preliminary in-situ results using conventional smartphone or tablet devices.     

Removal of individual off-flavour compounds in water during artificial groundwater recharge and during treatment by alum coagulation/sand filtration

The removal of individual off-flavour compounds during artificial groundwater recharge has been compared to the removal of such compounds during conventional alum coagulation/sand filtration. By using an evaluation technique based on gas chromatography with both instrumental and sensory detection (“column sniffing”) it was shown that alum coagulation/sand filtration had no significant effect on any of the off-flavour compounds that could be detected in the raw water samples (geosmin, 2-methylisoborneol, 2-isopropyl-3-methoxypyrazine, 2,4,6-trichloroanisole, 1-octen-3-one, 1-nonen-3-one, dimethyl trisulphide and a number of unidentified muddy or musty odours). During artificial groundwater recharge in sand and gravel ridges, however, the concentrations of all these compounds were substantially reduced, thus proving that artificial groundwater recharge is not only a suitable method for water storage but can also be an effective method for removing muddy and musty odours. The successful use of the column-sniffing technique for evaluating water treatment methods has shown the potential of this technique in resolving some of the present disagreements concerning the effectiveness of different treatment methods for removing tastes and odours from water.     

地质雷达信号分析的双正交小波预测反褶积法

为了降低电磁波衰减、噪声干扰等因素对地质雷达检测效果的影响,提出一种双正交小波预测反褶积法(PDBW法)。在PDBW法中,针对地质雷达检测信号选取具有最小重构误差的双正交小波基,运用该小波基将地质雷达检测信号分解成不同频段的时域子信号,对各频段的时域子信号进行预测反褶积等滤波处理,再对处理后的子信号进行重构变换,得到PDBW法的处理结果。将PDBW法用于实验检测信号处理,并将处理结果与预测反褶积法的处理结果进行比较,结果表明:PDBW法能有效压制多次回波干扰,准确识别深部信号,显著提高深部信号信噪比,从而进一步改善地质雷达探测分辨率和图像分析的准确性。     

地球物理方法在古河道探测中的应用综述

古河道的探测对于防震减灾、城市规划和地下水资源合理开发利用具有重要意义。地球物理方法与以往常规方法相比,大大提高了古河道探测的精度和深度,具有成本低、效率高的优点。本文介绍了近年来古河道探测采用的电测深法、高密度电法、瞬变电磁法、探地雷达、地震影像法、地震属性分析、地震沉积学等方法的基本原理与应用概况,为今后古河道探测方法的选择提供借鉴经验。针对古河道的埋藏深度与地质特征,一方面需要确定不同物探方法的有效性,另一方面需要采取综合物探方法进行探测,以提高古河道识别的准确性。