【作者】 易晓峰；

【导师】 林君；

【作者基本信息】 吉林大学 ， 测试计量技术与仪器， 2014， 博士

【摘要】 我国地下工程施工密度大，工程种类多，所面临的地质条件异常复杂，受地质灾害特别是水灾害隐患的威胁十分严重。目前已有的地下工程水害检测方法都是通过测量围岩结构、地层电性等参数间接推断突涌水体的位置和大小，属于间接探测方法。磁共振方法作为目前世界上最为行之有效的地下水直接探测方法，能够对突涌水体的含水量、孔隙度、含水层位置等水文地质参数进行直接探测。但是由于受到地下工程狭窄空间影响，进行磁共振方法探测必须缩小天线尺寸，由此引起的小尺寸天线获取信号微弱、激发能量输出效果差、探测系统性能要求苛刻等技术难题，使得这种方法在国内外还没有成功应用到地下工程中。本文针对磁共振技术应用于地下工程中所面临的技术难题，从全空间磁共振响应计算、米级分离式天线设计、仪器系统关键技术研制、模拟场地实验验证以及在实际工程现场中应用等方面开展工作，取得的主要研究成果如下：1、针对地下工程的特殊应用环境，本文给出了适用于全空间环境下的米级分离式多匝环形天线的信号响应计算公式，并根据实际目标水体模型的属性进行磁共振信号响应计算和仿真，为地下工程的磁共振探测提供理论基础。2、针对米级磁共振接收天线甚微弱信号获取问题，对接收天线系统建模，提出了接收天线性能评价方法，给出了接收天线最优化设计流程，确定了能够应用于隧道、矿井等地下工程中米级接收天线最佳参数，使接收天线对微弱信号的检测能力提高至纳伏级。3、针对狭窄地下空间发射天线激发能量受限问题，在分析了发射天线系统的性能影响因素基础上，给出了发射天线的最优化设计流程，确定了发射天线最佳参数，将天线激发能量提高了65%。同时结合实际情况，研究了地下工程中金属支护结构对发射电流的影响，提出了基于距离参数的发射电流改善措施，保证了地下工程中米级发射天线的能量输出效果。4、针对多匝天线获取信号死区时间过长问题，在发射系统和接收系统中进行双重抑制，加速关断时间，同时利用变Q原理对切换装置的阶跃响应进行消除，将多匝天线的死区时间从60ms缩短至18ms，提高了探测信噪比和初始信号的准确度。5、针对信号微弱、检测系统门槛过高问题，本文提出了前端电路匹配方法，通过对离散电容的连续化设计，提高了高感接收天线的中心频点稳定度，最大传递系数偏差小于2.8%，同时通过分析匹配电阻对天线传递系统的影响，将天线系统的传递系数进一步提高，保证了纳伏级甚微弱磁共振信号的有效提取。6、针对地下工程环境中的测量效率问题，给出了利用组合充电方式的系统快速充电方法，在保证最大充电误差小于1%的基础上，将充电速度提高了近5倍，同时设计了精度达到±0.01mH电感参数快速测量装置，使仪器能够在复杂的电磁环境中快速确定天线参数，提高了系统的工作效率。7、本文在已知水文地质参数的实验场地中开展了小尺寸磁共振探测天线的实测实验，分别利用6m、4m和2m天线获得了信噪比达到4.5以上的高质量的磁共振信号，有效证明了米级天线在地下工程中进行探测的可行性。本文取得创新性的研究成果主要有以下几点：1、针对地下工程中传统方法探测地下水害时，无法直接获取水文地质参数、量化困难等不足，首次提出了基于米级天线的磁共振技术进行水灾害隐患直接探测方法，实现了地下工程中灾害水体水文地质参数的定量探测。2、提出了一种米级探测天线性能评价方法，通过建立特征参数、传递系数与天线性能的约束关系，完成了最佳参数的探测天线设计。首次在地磁场环境下，利用所研制的天线（6m级、4m级、2m级）获得了信噪比达到4.5以上的高质量磁共振信号，填补了磁共振技术在这一领域的研制空白。3、针对微弱信号获取困难、检测分辨率过低等问题，提出了一种米级接收天线的前端电路调理方法，用多匝接收天线精密匹配、短死区时间控制、宽带锁相滤波等关键技术，实现了纳伏级甚微弱磁共振信号的提取。4、针对多匝探测天线关断时间过长问题，提出了高电感探测天线的阶跃响应控制方法。采用快速关断与剩余能量吸收、基于变Q原理的震荡抑制等技术手段，将多匝天线的死区时间从60ms缩短至18ms，改善了能量释放和振铃效应对初始信号的影响，为探测数据的精确反演提供了有效保障。本文首次利用所研制的米级探测天线和仪器系统在沪昆高速铁路贵州段、金温高速铁路温州段、锦屏水电站二期工程等多个隧道中进行水灾害隐患磁共振探测，取得了良好的工程应用效果，证明了磁共振方法在地下工程中对水灾害隐患探测的有效性。通过本文的研究，拓展了磁共振探测方法的应用领域，为直接有效的解决地下工程不良水体危害问题提供了研究基础和技术保障。更多还原

【Abstract】 China has extremely high density of underground construction, many kinds ofgeological engineering, and faces complex geological conditions and serious disasters,particularly the risk of water-induced disaster.Currently, the detection methods ofunderground water are all based on the rock structure or electrical parameters of theformation to indirectly determine the location and size of the sudden and gushingwater body, which belong to the indirect detection method. Magnetic ResonanceSounding method for direct detection of groundwater is the most effective method inthe world, which is capable of direct detection ofthe hydrogeological parameters, likewater content, porosity and aquifer location of sudden and gushing water body.However, due to the influence by the confined space in the underground,MRSmeasurementmust reducethe antenna size. Furthermore, the small size of the antennacauses very weak signal, poor excitation energy output and high detection systemperformance and other difficult technology problems. Therefore, this method has notbeen applied successfully to the underground project all around world.This paper focuses on taking MRS technology to apply for solving thesetechnical problems in the underground engineering. I have calculated the whole spaceresonance response, designed the small size of separated antenna, developed the keyparameters of the instrument, simulated the field experiments, and applied in theactual project sites. The main research results obtained are as follows:1. As for the special underground engineering environment in the applications,this paper gives the calculation formulas for the separated multi-turn antenna withsmall size, which is suitable for the whole-space environment, and calculates themagnetic resonance sounding signal response based on the actual target water bodymodel,which provide the theoretical basis of the magnetic resonance soundingmeasurement in the underground engineering.2. As for the problem that the obtained signal is very weak because of the smallsize of the magnetic resonance sounding antenna, this paper models the receivingantenna system, proposes a method for evaluating the performance of the receivingantenna. I propose the receiving antenna optimized design process, and identify thekey parameters of the6-m,4-m and2-m side of rectangular receiving antenna. Thereceiving antenna has been improved by a factor of4.8,which can be applied in thetunnels and mines.3. As for the problem that the limitation of excitation energy transmitting antennawhich is caused by the narrow underground space, this paperanalyses the factorsaffecting the performance of the transmitting antenna system and give the most optimized design process of the transmitting antenna and identify theparameters.While ensuring the depths, the antenna energy efficiency is improved by65%.Combining with the actual situation, I discuss the effect of the emission currentwith metal supporting structure in the underground engineering and propose thecontrol method based on the distance parameters of the transmitting current.4. As for the problem that long dead time for multi-turn antenna, this papercarries out a dual inhibition from the transmitting system and the receiving system toaccelerate the turn-off time. Meanwhile, according to the variable Q principle, I usethe switching unit to eliminate the step response. This method shorts the dead time inthe small detection antennas from60ms to18ms, and improvesthe accuracy of thedetection SNR and hydrological parameters.5. As for the problem that weak signal and high threshold entering the detectionsystem, this paper proposes a method to match the front-end circuit. Throughcontinuous design of the discrete capacitor, I improve the stability of the frequencycenter of the high inductance-receiving antenna. The maximum transfer coefficientdeviation is less than2.8%. At the same time, the matching resistance influence onantenna transmission system is analyzed. Further improve transfer coefficient of themeter-antenna system,to ensure the effective extraction of very weak magneticresonance signals on nanovolt scale.6. As for the problem that measuring efficiency in the underground engineeringenvironment, this paper presents a fast charging method that uses combination ofcharging way to increase the charging system speed and accuracy. On the basis oferror of less than1%, the guaranteed maximum charge is fasterby5times. Meanwhile,I design a sweep method to quickly determine the inductance parameter. Antennaparameters can be determined rapidly in complex electromagnetic environment,which improve the work efficiency of the system. The accuracy of the antennainductance is determined of±0.01mH.7. Based on the known hydrogeological parameters field, I have carried outthemagnetic resonance soundingmeasurement with the small size antennas and obtaineda high quality magnetic resonance sounding signalwith more than4.5signal to noiseratio by using6m,4m,2m antenna,respectively. I have effective proved thefeasibility of the meter scale the antenna in the underground engineering.This paper has made the innovative research results as following:1. This paperaims at that the traditional method in the underground engineeringcan’t obtain the hydrogeological parametersof disaster-induced groundwater and hasdifficult to quantify. For the first time, I propose a totally new method that detects directly the hidden water hazards using MRS technology with the meter scale antennatoachieve a quantitative detection of hydrogeological parameters of disaster-inducedwaterin the underground engineering.2. I propose anevaluation methodfor the performanceof meter scale detectionantenna.Through establishing the constraint relations of the characteristic parameters,the transfer coefficient and the antenna performance, I complete the antenna designwith the optimal parameters.For the first time,I have used the developed antenna (6-m,4-m, and2m) to obtain the high quality of magnetic resonance sounding signalwiththe signal to noise ratio of more than4.5in the earth’s magnetic field environments,which fills the blank in magnetic resonance technology area.3. This paper aims at the problems thatit is difficult to get the weak signal and theresolution is too low to detect,proposes a front circuit conditioning method for themeterscalereceivingantenna. The method applies theprecision matchingof multi-turnreceiving antenna, short dead-time control, broadband phase-locked filtering andother key technologies to achieve very weak magnetic resonance soundingsignalsextraction of nanovolt.4. This paperaims at the problem thatthe long turn-off time of the multi-turnantenna, proposes amethod to control the high inductance antennastep response.Thismethod uses fast turn-off, residual energy absorption technique and shock suppressiontechnique based on the change Q principleto reduce the impact of energy release andringing effect on the initial signal, whichreduce the dead time from60ms to18ms,and provide effective protection of the result of the data inversion.This paper firstly uses the developed meter scale antenna and magneticresonance sounding system in Guizhou section of Shanghai-Kunming high-speedrailway， Wenzhou section of Jinhua-Wenzhou high-speed railway and Jinpinghydropower station phase II and other tunnels to detect hidden water hazards andachieved good engineering application results. These results confirm the effectivenessof the magnetic resonance sounding method for the disaster-inducedwater detection inunderground engineering. Through the research in this paper, I expand the scope ofapplication of magnetic resonance sounding area, solve directly and effectively thewater hazard problems in the underground engineering and provide the technicalsupport for basic research.更多还原