Discussion on the application prospect of the transient electromagnetic method based on the dual launcher and mine advanced detection

The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is rarely reported in the detection of pipelines in urban geophysical exploration and the application of coal mines. Based on this, this paper realizes the equivalent anti-magnetic flux transient electromagnetic method based on the dual launcher. The suppression effect of this method on the blind area is analyzed by physical simulation. And the detection experiment of underground pipelines is carried out outdoors. The results show that the dual launcher can significantly reduce the turn-off time, thereby effectively reducing the impact of the blind area on the detection results, and the pipeline detection results verify the device’s effectiveness. Finally, based on the ground experimental results, the application prospect of mine advanced detection is discussed. Compared with other detection fields, the formation of blind areas is mainly caused by the equipment. If the dual launcher can be used to reduce the blind area, the accuracy of advanced detection can be improved more effectively. The above research results are of great significance for improving the detection accuracy of the underground transient electromagnetic method.

Experiment in metal disturbance during advanced detection using a transient electromagnetic method in coal mines

Tunneling machines, or excavators, are large and good conductors and affect the reliability of data gathering and interpretation in advanced detection using transient electromagnetic methods. In our experiment, we used a coincident-loop and central loop type of configuration, where the coil plane l） vertical to and 2） parallel to the working face. A SIROTEM instrument at different locations was used to observe the transient electromagnetic responses of the excavator and to analyze the response amplitudes. The result shows that the tunneling machine affects the advanced detection data and is related to the way the coil is coupled. When the excavator is 6 m from the observatory, the interference of tunneling machine can be ignored.

Experimental analysis on bolt interference during advanced water detection with the mine transient electromagnetic method

During advanced water detection using the transient electromagnetic method, the exploration effect for water-rich area is often poor due to the interference of bolts that are distributed in different positions in working face. Thus, the study on the interference characteristics of bolts in different states has important directive significance for improving the acquisition quality and data processing method in water detection. Based on the analysis of the distribution laws of magnetic field excited by small multi-turn coincident loop in full space of homogeneity, the test on the interference of bolts has been designed in the mine. Through drilling 18 holes around the overlapping coil in the working face, mass data are collected in order with the posi- tion change and the exposed bolt length. The results of comprehensive data analysis show that the transient electromagnetic field is strongly interfered as the distance between the bolt and the center of the coil is less than 3 m, and the interference varies greatly as the distance varies. On the other hand, the field induced by the bolts can be ignored as the distance exceeds 3 m. The findings can help to improve data acquisition and correction during advanced water detection when using the transient electromagnetic method.

Prediction Technology of Buried Water-Bearing Structures in Coal Mines Using Transient Electromagnetic Method

Buried water-conducting and water-bearing structures in front of the driving head may easily lead to water bursts in coal mines. Therefore,it is very important for the safety of production to make an accurate and timely forecast about water bursts. Based on the smoke ring effect of transient electromagnetic fields,the principle of transient electro-magnetic method used in detecting buried water-bearing structures in coal mines in advance,is discussed. Small multi-turn loop configurations used in coal mines are proposed and a field procedure of semicircular sector scanning is presented. The application of this method in one coal mine indicates that the technology has many advantages compared with others. The method is inexpensive,highly accurate and efficient. Suggestions are presented for future solutions to some remaining problems.

Feasibility study of the transient electromagnetic method for chamber blasting misfire detection and recognition

In this paper,transient electromagnetic method was used to carry out the feasibility study on the detection and recognition of chamber blasting misfire.Firstly,an electromagnetic background field was established in the test;secondly,a benign conductor was preset in the chamber,and then the background field was eliminated after the electromagnetic field was measured;thirdly,the transient electromagnetic field was measured again after blasting;at last,the chamber blasting misfire was detected and recognized by comparing the change of eddy current field of the preset benign conductor before and after blasting.The test results showed that:When the buried depth of aluminum box target was no more than 30 m,transient electromagnetic method can clearly identify the position of the aluminum box;when the buried depth of aluminum box was more than30 m,the buried depth and position of the aluminum box was not sure due to the unknown level of secondary eddy current field generated by aluminum box.

Calculation and application of full-wave airborne transient electromagnetic data in electromagnetic detection

Airborne electromagnetic transient method enjoys the advantages of high-efficiency and the high resolution of electromagnetic anomalies,especially suitable for mining detection around goaf areas and deep exploration of minerals.In this paper,we calculated the full-wave airborne transient electromagnetic data,according to the result of numerical research,the advantage of switch-off time response in electromagnetic detection was proofed via experiments.Firstly,based on the full-wave airborne transient electromagnetic system developed by Jilin University(JLU-ATEMI),we proposed a method to compute the full-waveform electromagnetic(EM)data of 3D model using the FDTD approach and convolution algorithm,and verify the calculation by the response of homogenous half-space.Then,through comparison of switch-off-time response and off-time response,we studied the effect of ramp time on anomaly detection.Finally,we arranged two experimental electromagnetic detection,the results indicated that the switch-off-time response can reveal the shallow target more effectively,and the full-waveform airborne electromagnetic system is an effective technique for shallow target detection.

Research on application of transient electromagnetic technology in coal mine

Studied the principle of transient electromagnetic method in coalmine and solved the computation of the whole time apparent resistivity and the relation between apparent resistivity and exploration depth and so on. Studied the work method of transient electromagnetic method in coalmine and obtained reasonable arrangement way. Studied data processing and explanation method of transient electromagnetic method and obtained high quality electric section. Finally the purpose to detect water-bearing body and water-bearing structure in front of roadway in advance, and detect the water-bearing property of the roof and floor rock layer of coal face were realized by use of transient electromagnetic method.

钻孔瞬变电磁法扫描探测RCQPSO-LMO组合算法2.5D反演

利用钻孔进行超前探测地质构造及含水体是地下开挖工程中的常规手段,如何利用这些钻孔进行钻孔瞬变电磁法扫描探测,从而实现钻孔孔壁外围地质异常体的精细探测,对实现地下工程地质透明化具有重要的指导意义.本文提出钻孔瞬变电磁法扫描探测2.5D反演的数据解译方法,首先针对随机性反演算法时效性低,易陷入局部最优解,而确定性反演算法依赖初始模型的问题,提出了组合策略的量子粒子群优化算法用来随机搜索最优初始模型.在此基础上,利用Levenberg-Marquarat方法求解Occam反演的目标函数,形成了RCQPSO-LMO组合算法进行2.5D反演,通过对比组合算法和单一算法,验证了组合算法具有更精确的反演结果.其次结合屏蔽条件下扫描探测,对比分析了有无屏蔽的2.5D反演结果,通过设定屏蔽系数对非探测方向信号进行部分压制,可以较好地解决钻孔径向扫描探测中对非探测方向信号部分屏蔽下的反演及成像.最后建立三组理论模型进行组合算法2.5D反演,结果表明:组合算法反演结果与理论模型的一致性较好,对低阻异常体的反演精度较高,验证了组合算法对钻孔孔壁外围低阻异常体具有较高的反演精度和分辨能力.

钻孔瞬变电磁法方位线圈扫描探测定位方法

利用掘进巷道超前探水钻孔进行钻孔瞬变电磁法探测钻孔孔壁外围远距离含水体,避免了常规测井方法仅能探测钻孔孔壁岩层的“一孔之见”。目前钻孔瞬变电磁法受全空间效应的影响,接收到的单分量响应不能判别异常体方位;多分量响应可以近似判断异常体的大致方位,但难以通过成像等直观有效的方法对其进行精确定位。基于钻孔瞬变电磁法和方位电磁波测井相关理论,提出了钻孔瞬变电磁法方位线圈扫描探测定位方法,采用方位线圈作为探测装置,减小线圈互感,增强钻孔瞬变电磁法的探测效果。同时,通过改变线圈旋转角,对钻孔孔壁进行360°扫描,形成钻孔径向全方位探测,旨在对钻孔孔壁外围岩体中的低阻体进行精确定位。首先推导方位线圈的互感解析表达式,探讨方位角对方位线圈互感的影响,通过数值计算确定最佳方位角取值。分别建立均匀介质和含低阻异常体的钻孔全空间三维地质-地球物理模型进行瞬变电磁场数值模拟,分析方位线圈的瞬变电磁法扫描探测多分量响应特征,总结方位线圈扫描探测瞬变电磁响应规律,确定了钻孔瞬变电磁法方位线圈扫描探测定位方法,即通过钻孔轴向和径向的瞬变电磁响应特征判别钻孔孔壁外围岩体中低阻异常体的位置。最后建立含2个低阻体的地质-地球物理模型,采用最佳方位角的方位线圈进行数值实验,验证了该方法能有效地判别低阻异常体的方位。研究表明:钻孔瞬变电磁法方位线圈扫描探测结果可以较好地反映钻孔径向外围岩体中低阻异常体引起的瞬变电磁场异常,全空间视电阻率成像结果分辨率较高。依据钻孔轴向和径向的瞬变电磁响应特征,钻孔瞬变电磁法方位线圈扫描探测定位方法对钻孔孔壁外围岩体中的低阻异常体具有较高的分辨率及定位精度。研究结果可以为钻孔瞬变电磁法方位线圈扫描探测定位方法的实际应用提供理论依据。

滇中引水工程隧洞综合超前地质预报分析及应用

针对隧洞施工过程中不同工程地质条件下何种超前地质预报方法预测更为准确、更为适用和单一方法精确度不够、适用性不强的问题,分别介绍了基于地震波法的长距离隧洞超前地质预报技术和基于电磁法的中、短距离隧洞超前地质预报技术原理及特点,依据其工作原理、工作方式、预报距离等特点,探讨了不同超前地质预报方法的优、缺点及其最适用的工作场景,总结出一套实用性强的综合超前地质预报流程。依托滇中引水工程大理Ⅱ段两个隧洞的工程实例,利用所提出的综合超前地质预报流程,分别介绍了结合长距离的隧道地震预报(TSP)法、中短距离的瞬变电磁法和探地雷达法对断层破碎带和裂隙水等不良地质体的综合预报研究。首先,通过长距离预报方法对地质灾害危险程度进行分级、识别高危地段,再通过短距离预报方法对不良地质体进行更精确的识别与定位,综合分析3种超前地质预报方法的地球物理响应特征,可以推断出不良地质体的类型及其空间分布特征;其次,通过探地雷达探测溶蚀波场特征的案例分析,可以推断出溶蚀的物性特征、规模及其空间分布特征。预报结果与隧洞掌子面开挖揭示的结果基本一致,验证了3种超前地质预报方法预报隧洞不良地质体的可靠性,也证实了所提出的综合超前地质预报流程的实用性,有助于指导物探工作者对不良地质体进行更精确的预报,确保隧洞施工安全。

钻孔瞬变电磁法接收线圈定向屏蔽物理模拟研究

钻孔瞬变电磁(BTEM)扫描探测方法可以利用巷道已有超前探查钻孔,通过旋转置于钻孔内收发线圈对孔壁外围隐蔽地质异常体进行扫描探测,因收发装置位于钻孔内,不仅避免了巷道内电气设备和金属物的电磁干扰,而且可以提高钻孔利用率,减少钻探工作量。然而,钻孔瞬变电磁法受全空间效应的影响,在扫描探测过程中,以收发线圈法线方向为探测方向接收异常体二次场信号的同时,还易受到其他方向信号的叠加干扰。若无法有效压制干扰信号,将直接影响对钻孔孔壁外围地质异常体的精确定位。利用屏蔽的方法,在接收线圈上安装屏蔽罩,尽可能保留线圈法线与屏蔽罩开口一致的探测方向的响应信号,而对其他方向的信号进行压制,从而实现钻孔孔壁径向一定范围内指向性探测。首先通过物理模拟实验探讨了不同匝数、尺寸的收发线圈对瞬变电磁场响应特征的影响,对适用于钻孔内的收发线圈参数进行组合优选。然后针对所要屏蔽的电磁波,选择不同种类的屏蔽材料,开展不同材料对不同方向电磁波的屏蔽效果实验。通过对比探测方向和其他方向的感应电动势,证实以泡沫镍制作的屏蔽罩能有效地压制非探测方向的干扰信号。通过实验分别对屏蔽罩的不同形状、磁导率等物性参数进行瞬变电磁场响应特征对比分析,并探讨屏蔽罩开口角度与定向屏蔽效果的关系,优化定向屏蔽罩参数,增强屏蔽效果。最后使用参数优化后的收发线圈和定向屏蔽装置进行钻孔瞬变电磁法径向断面扫描探测现场实验,采用基于混合分布的混沌量子粒子群和Levenberg-Marquarat及Occam组合算法的反演方法进行电阻率成像。研究表明:以泡沫镍为屏蔽材料,安装在接收线圈上的弧形屏蔽罩定向屏蔽效果较好,可以有效地压制钻孔瞬变电磁法扫描探测过程中非探测方向的信号干扰,且能较大程度的保留探测方向的异常响应信号,进而可以实现对钻孔孔壁外围隐蔽地质异常体的精确定位。

瞬变电磁法和地震反射波法在不良地质洞段超前地质预报中的应用

物探方法是超前地质预报的主要手段,通过不良地质体与围岩物性参数差异,及时发现和预测地质条件的变化。较完整一完整围岩岩体物性参数与不良地质体物性参数存在较明显差异,有利于分辨出不良地质体;但是在地质条件差洞段的不良地质体与围岩岩体物性参数差异极小,不利于分辨出不良地质体,使得岩体质量情况和地质灾害风险预报难度极大。本次采用瞬变电磁法与地震反射波法的综合物探法,在滇中引水工程大理Ⅱ段Ⅴ_(特)类岩体开展专项超前地质预报工作,主要利用岩体视电阻率、应力梯度、纵波波速、横波波速等参数对未开挖段岩体质量和可能存在的地质灾害风险进行预测。创造性地通过“日进尺”这一指标间接对开挖岩体破碎程度进行评价,经对比,预报成果中符合长度占实际开挖过程中问题段长度的85.1%,预报结果与开挖成果较为吻合;此外,对坍塌失稳段、突泥涌水段也有明显反映,为该方法组合在不良地质洞段超前地质预报中的应用提供了借鉴。

古兜山隧道富水段探测与处置技术研究

为探明古兜山隧道富水情况,通过超前钻孔、瞬变电磁法探测隧道富水段情况;针对古兜山隧道的富水情况,开展现场注浆止水加固试验研究,提出富水区注浆止水关键技术;综合考虑隧道地下水排放量与植被生态的平衡,给出隧址区的地下水允许排放量。研究结果表明:选择普通水泥-水玻璃双液浆用于钻孔揭露隧道涌水量较大的区域,确保注浆效果;综合考虑地下水压力、地层岩性、浆液的性质和浓度及注浆扩散半径等因素,确定注浆终压取值为5~6 MPa;针对植被、生态环保要求,按2年内恢复原始地下水位,确定泄洪口区、水库连接区及隧道近出口区的地下水允许排放量。

钻孔瞬变电磁法拟地震全波形反演

钻孔瞬变电磁法是将发射与接收装置布置于钻孔中,因距离目标体近,探测精度得到提升,有利于煤矿钻孔周围含水体精细探测.常规的钻孔瞬变电磁法通过多分量响应近似判断异常体方向,难以对异常体的边界位置进行刻画,而且因瞬变电磁场的扩散特征,常规的反演方法对地质异常体的边界位置分辨率偏低.针对以上问题,结合钻孔瞬变电磁法扫描探测定位方法,通过波场转换将钻孔瞬变电磁法数据转换成虚拟波场数据,然后进行全波形反演与成像.针对虚拟波场直达波能量较强且属于干扰波,采用剪切波变换去除虚拟波场直达波,避免了虚假界面;其次由于波场转换过程中核函数病态性强的特点,引入虚拟电导率,降低了虚拟波场速度,从而降低了波场转换核函数病态性;为了对虚拟波场进行高精度反演与成像,分别采用阻尼最小二乘法和伴随状态法实现虚拟波场全波形反演.结合钻孔瞬变电磁法探测的数值实验得出阻尼最小二乘全波形反演方法的反演结果更加准确,可以实现对钻孔孔壁外围地层信息的精细刻画,提高了钻孔瞬变电磁法扫描探测的效果.

地面物探技术在隧道掘进破碎带区段的应用

广佛环大太区间在隧道施工过程中出现多次掉块及局部地段沉降等现象,为查明掘进破碎带区上部的发育情况,采用高密度电阻率法和瞬变电磁法两种地面物探技术进行综合探测,结果表明:高密度电阻率法具有快速、高效等优点,能较好地反映出浅部的不良地质体;瞬变电磁法具有灵活、探测深度大等优点,对探测中深部的不良地质体有一定的效果。该组合物探技术由浅到深基本探明了隧道范围上方的地质变化情况,解释了引起隧道掉块及局部沉降的原因,为下一步的施工处理提供指导性意见。

瞬变电磁法在矿山巷道超前预报系统构建中的应用研究

利用CUGTEM-GKⅡ瞬变电磁仪对矿山巷道的超前勘探工作进行实时物探,并形成三维模型成像结果,给出了矿山岩层地下水涌水量、巷道顶板及两帮位移量等预警数据。其中,机器学习算法整合深度卷积神经网络、多列神经网络、数据二值化输出、模糊决策矩阵预警等算法,给出了覆盖范围较大的粗略预警结果和覆盖范围较小的精细预警结果。经仿真分析,粗略预警结果和精细预警结果均表现出一定的数据敏感性,且精细预警可以在巷道掘进问题岩层前24 h给出较高敏感度的预警结果。

OCTEM法探测地下空间地质病害体的应用研究

城镇地下空间地质病害体造成地面塌陷事故时有发生,对人民群众的生命财产安全构成巨大威胁。采用地球物理方法探测和预报地下空间地质病害体是预防城镇地面塌陷事故的重要方案。瞬变电磁法(TEM)是探测地下空间地质病害体的重要方法之一。等值反磁通瞬变电磁法(OCTEM)采用免接地、小体积、弱耦合的收发一体小型天线,便于在城镇硬化地面及施工空间受限的场地进行快速探测。本文结合理论计算和实际应用来研究OCTEM对地下地质病害体的探测能力。首先基于矢量有限元实现OCTEM三维正演,研究不同地电类型地质病害体的OCTEM响应特征。根据地下地质病害体的电性特征,构建了纯低阻型、纯高阻型、低阻-高阻复合型3类地质病害体地电模型,对比分析不同地电类型的地质病害体的异常响应,并计算包含地质病害体时的响应与不包含地质病害体时的背景响应之间的相对异常。计算结果表明:OCTEM对纯低阻型和低阻-高阻复合型地质病害体比较敏感,对纯高阻型地质病害体相对不敏感。对于低阻型或低阻高阻复合型地质病害体,低阻部分与围岩电阻率差异越大、厚度越大、埋深越浅,则相对异常越大,越容易被探测。随着深度加大,OCTEM探测分辨能力将减小。最后,通过在湖南浏阳某村镇试验剖面探测地下岩溶地质病害体案例,分析OCTEM的探测效果。

基于瞬变电磁法的张家峁煤矿地层富水性特征研究

煤矿地层的富水性探测对于煤矿的防水与治水工作至关重要。张家峁煤矿现阶段主采2-2煤层,面临上部基岩风化含水层和工作面前方火烧岩涌水的水害风险。鉴于瞬变电磁法对富水区、采空区、含水构造等高导异常体的高灵敏度等优势,本研究采用地面瞬变电磁法对该煤田西部特定区域2-2煤层上覆的基岩、风化带、第四系岩层以及烧变岩的富水性进行探测,在四个地层分别探查出低阻异常区6处、9处、9处和2处,并结合钻孔、地层、水文、地形和磁法探测成果等多元资料以及低阻异常区的可靠性,对低阻异常区的成因分别进行了综合分析,这可为该区域煤层开采防水与治水工作的规划与执行提供科学依据。同时,本研究也可为瞬变电磁法在其它地区地层富水性探测中的应用提供一套全面的数据采集、处理、反演以及分析与解释的参考与借鉴资料,以推动该技术在煤矿地层探测领域的进一步发展与应用。

瞬变电磁法在煤矿老窑采空区积水探测中的应用

以某煤矿6-1采区为研究案例,根据采区地质水文及地球物理电性特征情况,合理在采取内容实施数据采集,对数据实施预处理后,从全域视电阻率断面图和全域视电阻率切面图2个角度实施煤矿老窑采空区积水探测分析。根据分析结果对采取1#和2#煤层采空区积水范围进行综合解释说明,最后采用钻孔探测法进行采取采空区积水情况验证分析,有效确认瞬变电磁法的应用价值。

“长掘长探”技术在TBM掘进巷道中的应用研究

针对韩城矿区所属煤矿普遍存在奥灰含水层积水、小窑积水等水害隐患对TBM掘进巷道安全构成严重威胁的情况,迫切需要一种适用于TBM掘进工程的新型水害超前探查技术。结合矿区实际情况,提出了一种适用于煤矿井下TBM掘进巷道的水害探查技术即“长掘长探”新技术。该技术将煤矿井下定向长钻孔钻进技术和井下孔内瞬变电磁技术进行有机地结合,分别对分支孔成孔技术和数据重构技术进行技术改良,通过优选工程技术方案,选取适配的设备及钻具,使用新型孔内瞬变电磁探测仪器,有效解决了韩城矿区TBM掘进巷道无法“随掘随探”的煤矿井下超前水害隐患探查技术难题,提高了巷道快速掘进地质超前的探测效率和成果精度。应用证明,该技术探测成功率高达95.11%,掩护成功率可达91.53%,同时节约了24%的工期,探得一处富水异常区误差最大仅有0.3 m,该技术适合在类似矿井巷道掘进中推广应用。