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日山东科技大学硕士学位论文摘要摘要地下矿产的开采，往往会形成大面积的采空区，这些采空区打破了周围岩石圈应力平衡的状态，会导致塌陷等地质灾害的发生。地下塌陷的产生，会引起地下水的枯竭，破坏地表的耕地，甚至会影响到当地的房屋，铁路、公路等基础设施，威胁到居民的财产跟生命安全。EH-4大地电磁法起源于大地电磁法，其操作简单，能适应恶劣的环境条件，对煤炭采空区的有一定的勘探效果。EH-4大地电磁法对不同的地下介质会产生不同的响应特征，这也是本文主要的研究内容。
本文第一部分以EH-4大地电磁测深法的基本理论为基础介绍了该仪器的工作机理、工作特点。第二部分是本文的主要研究部分，通过COMSOL软件进行了大地电磁数值正演模拟，针对几种与实际工作相关的地电模型，得出了对应的响应特征。第三部分是关于榆林地区煤矿采空区勘探的事例，举例是为了验证所建立的地电模型是否对实际工作具有指导意义，该事例以测区采空区与积水区的勘探过程与勘探结果进行对比分析，得出EH-4大地电磁法在此领域的应用特点。
本文通过数值正演模拟研究得出：
大地电磁测深法所用到的正常频段区间可以满足大多数的异常体探测。电场Ex与视电阻率平面等值线图可以较好的反映异常体的形态特征，相位等值线图接近异常体的形态，但异常的响应不明显。电场Ex与视电阻率平面等值线图对于低阻的异常响应比高阻要好，纵向分辨率要好于横向分辨率，在高阻异常存在时表现最为明显。
通过对勘探事例的研究得出：
EH-4对一定深度的地质勘探有较好的效果，而对浅部的信息存在盲区，尤其是浅部地层为低阻干扰的情况下；EH-4大地测深法穿透性好，可以对深部信息进行反映；EH-4大地测深法纵向分辨率较高，可以对一些不易察觉的构造，尤其是纵向上的异常进行较好的分辨，但对于高阻体的横向分布，却很难去判断出其分布的边界范围。
从以上得出的两种结论可以看出，此次建立的地电模型与所产生的参数曲线特征与实际的工程勘察效果有着很高的匹配度，对实际生产有着一定的指导作用。
关键词:
EH-4大地电磁测深法煤矿采空区数值模拟数据处理
I万方数据山东科技大学硕士学位论文摘要ABSTRACTMiningofundergroundminerals,tendtoformalargeareaofminedareas,theseminingareastobreakthebalanceofthesurroundinglithospherestate,willleadtosubsidenceandothergeologicaldisastersoccur.Undergroundsubsidence,willcausethedepletionofgroundwater,destructionofthesurfaceofthearableland,andevenaffectthelocalhousing,railways,highwaysandotherinfrastructure,athreattotheresidentsofthepropertyandlifesafety.EH-4electromagneticmethodoriginatedinthemagnetotelluricmethod,itsoperationissimple,canadapttoharshenvironmentalconditions,inthecoalminedareaexplorationhasacertaineffect.EH-4electromagneticmethodhavedifferentresponsecharacteristicstodifferentundergroundmedia,whichisthemainresearchcontentofthispaper.
ThefirstpartofthispaperintroducestheworkingmechanismandworkingcharacteristicsoftheinstrumentbasedonthebasictheoryofEH-4magnetotelluricsounding.Thesecondpartisthemainresearchpartofthispaper.ThegeomagneticnumericalforwardmodelingiscarriedoutbyCOMSOLsoftware,andthecorrespondingresponsecharacteristicsareobtainedforseveralgeoelectricmodelsrelatedtotheactualwork.Thethirdpartisabouttheexplorationofcoalmined-outareainYulinarea,forexample,toverifywhethertheestablishedgeoelectricmodelisinstructivetotheactualwork.Thecaseisbasedontheexplorationprocessandexplorationofmined-outareaandwaterareaTheresultsarecomparedandanalyzed,andtheapplicationcharacteristicsofEH-4magnetotelluricmethodinthisfieldareobtained.
Inthispaper,numericalforwardmodelingisusedtostudy:
Thenormalbandsegmentusedbythemagnetotelluricsoundingmethodcansatisfymostoftheanomalydetection.TheelectricfieldExandtheapparentresistivityplanecontourmapcanreflectthemorphologicalcharacteristicsoftheanomalousbody,andthephasecontourisclosetotheshapeoftheanomalousbody,buttheabnormalresponseisnotobvious.TheabnormalresponseoftheelectricfieldExandtheapparentresistivityplaneisbetterthanthehighimpedanceforthelowimpedance,andthelongitudinalresolutionisbetterthanthelateralresolutionandthemostobviousinthepresenceofhighimpedanceanomalies.
Throughthestudyofexplorationcases:
EH-4hasagoodeffectonacertaindepthofgeologicalexploration,
II万方数据山东科技大学硕士学位论文摘要whiletheshallowinformationontheexistenceofblindspots,especiallyshallowstratigraphyforthecaseoflowresistanceinterference;EH-4geodesypenetrationisgood,TheEH-4geodesymethodhasahigherlongitudinalresolution,anditcandistinguishbetweensomeimperceptiblestructures,especiallythelongitudinalanomalies,butthehorizontaldistributionofthehighresistivityisveryItisdifficulttodeterminetheboundariesofitsdistribution.hashighresolution,canreflectsomeimperceptiblestructures,fortheresistivitydifferencebetweenthestratacanalsobeabetterresolution.
Fromtheabovetwoconclusionscanbeseenthattheestablishedgeoelectricmodelandtheresultingparametersofthecurveandtheactualengineeringsurveyresultshaveahighdegreeofmatching,canguidetheactualproduction.Keyword:EH-4magnetotelluricsoundingmethod;Coalmined-outarea；NumericalSimulation；dataprocessing
III万方数据山东科技大学硕士学位论文目录目录1绪论.......................................................................................................................1
1.1论文选题及研究意义....................................................................................................11.2研究现状.......................................................................................................................11.3主要研究内容及技术路线...........................................................................................4
2EH-4大地电磁测深基本理论...........................................................................7
2.1大地电磁测深基本理论...............................................................................................72.2EH-4大地电磁法工作原理.......................................................................................102.3本章小结.....................................................................................................................13
3大地电磁法数值模拟.......................................................................................14
3.1大地电磁测深法正演理论.........................................................................................143.2不同地电模型数值模拟及分析.................................................................................173.3本章小结......................................................................................................................38
4EH-4数据处理方法研究.................................................................................39
4.1原始数据整理.............................................................................................................394.2数据处理.....................................................................................................................424.3图件生成与分析.........................................................................................................454.4本章小结.....................................................................................................................45
5EH-4大地电磁法在榆林地区煤矿采空区勘探中的应用............................46
5.1研究区概况.................................................................................................................465.2野外数据采集.............................................................................................................495.3图件解释与分析.........................................................................................................585.4图件对比分析.............................................................................................................62
6结论与展望.......................................................................................................69参考文献...............................................................................................................71致谢........................................................................................................................75攻读学位期间科学研究成果及奖励...................................................................76
IV万方数据
EH4大地电磁法在煤矿采空区勘探中的应用研究
