脉冲雷达透地探测煤岩实验研究
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摘要
传统的煤岩探测采用瞬变电磁、地震波、超声波和探地雷达等技术,发射和接收1 GHz以下的信号频率,不能兼顾探测深度和探测精度。综采工作面采煤机自动调高要求煤岩分界达到20 mm的检测精度,为此提出采用无线脉冲雷达穿透煤岩层的高精度深度探测技术。设计成单雷达芯片+射频电路的低功耗小型化的超宽带雷达,由脉冲产生器PG(Pulse Generator)发射亚纳秒级的窄脉冲电磁波形,输出中心频率为5. 3～8. 8 GHz、频宽为1. 65～4. 40 GHz和功率为-17. 2～-10. 5 dBm的超宽带UWB(Ultra-Wide Band)信号,输入电路采集从煤岩介质反射回来的峰峰值达54～72 m V的信号电压。超宽带雷达通过双Vivaldi型天线垂直于煤岩层贴近布置,发射天线发出低至-19 dBm的7阶高斯脉冲超宽带波段信号,接收天线以30 Gbps的速率采集512级深度回波信号,利用煤岩存在明显介电常数差异所产生的脉冲反射与发射信号的传播时延,与现场煤岩介电常数标定后计算出的电磁波传播速率相乘,来推算出煤层厚度以精确地确定出煤岩分界位置。根据煤层深度和介电常数的变化建立了煤岩探测的脉冲垂直分辨率、探测深度与信号采样时窗长度关系,确定采样时窗长度为256 ns,测量分辨率达到4 mm。为了直观地分辨出煤岩分界位置,以采集的脉冲信号数据绘制波形灰度图,深黑色和亮白色分别表示信号的波谷和波峰,代表了介电常数有较大差异的煤岩两种介质的分界位置,并通过波谷或波峰到起点的时间差计算出煤层的厚度。在留顶煤开采的综采工作面和巷道现场测试,测量煤层厚度的误差小于20 mm,能够在煤层未开采前检测出工作面顶煤和底煤的厚度,为采煤机自动调高提供精准的位置参考。
Technologies such as transient electromagnetic,seismic wave,ultrasonic wave and ground penetrating radar,etc.have been utilized in the traditional coal and rock detection to transmit and receive signal frequencies below1 GHz.However,utilizing these technologies cannot give consideration to both the detection depth and accuracy.As the coal-rock interface shall reach the detection accuracy of 20 mm according to requirements of the automatic horizon control of shearer in the fully mechanized coal mining face,the high-precision depth detection technology that pene-trates the coal and rock seam with the radio pulse radar is proposed. Low-power and downsizing UWB(Ultra-Wide Band) radar is designed with mono-radar chip+RF circuit.And it's the PG(Pulse Generator) that transmits a subnanosecond narrow pulsed electromagnetic waveform to output UWB signals at the center frequency ranging from 5.3 to8.8 GHz,the bandwidth ranging from 1.65 to 4.40 GHz and the power ranging from-17.2 to-10.5 dBm.Meanwhile,the input circuit collects the signal voltage of the peak-to-peak value ranging from 54 to 72 m V reflected from the coalrock medium.The UWB radar is arranged closely through the dual Vivaldi antenna being perpendicular to the coal and rock seam.The transmitting antenna sends 7 thorder Gaussian pulse UWB band signal as low as-19 d Bm,while the receiving antenna collects 512-depth return signals at a rate of 30 Gbps.In this way,the precise coal-rock interface location can be estimated through multiplying the propagation delay of pulse reflection and sending signals generated by the apparent difference of dielectric constant in the coal and rock by the electromagnetic wave propagation rate calculated after calibrating the dielectric constant of at the coal-rock site.Moreover,based on changes in the depth of coal seam and dielectric constant,the relationship of coal-rock detection among pulse vertical resolution,detection depth and length of the signal sampling window are established to determine that the length of sampling window is 256 ns with the measuring resolution reaching 4 mm.A waveform gray-scale map is drawn with pulse signal data collected for intuitively distinguishing the coal-rock interface location.To be specific,dark black and bright white in the map are the valley and peak of the signals,respectively,representing the interface locations of two media of coal-rock with great differences in the dielectric constant.In the meantime,the thickness of the coal seam is calculated by the time difference from the valley or the peak to the starting point.In the fully mechanized coal mining face and roadway field test for roof coal mining,the thickness of the coal seam measured with the error less than 20 mm can detect the thickness of the roof coal and the floor coal of the working face in the virgin coal,providing accurate location reference for the automatic horizon control of the shearer.
Technologies such as transient electromagnetic,seismic wave,ultrasonic wave and ground penetrating radar,etc.have been utilized in the traditional coal and rock detection to transmit and receive signal frequencies below1 GHz.However,utilizing these technologies cannot give consideration to both the detection depth and accuracy.As the coal-rock interface shall reach the detection accuracy of 20 mm according to requirements of the automatic horizon control of shearer in the fully mechanized coal mining face,the high-precision depth detection technology that pene-trates the coal and rock seam with the radio pulse radar is proposed. Low-power and downsizing UWB(Ultra-Wide Band) radar is designed with mono-radar chip+RF circuit.And it's the PG(Pulse Generator) that transmits a subnanosecond narrow pulsed electromagnetic waveform to output UWB signals at the center frequency ranging from 5.3 to8.8 GHz,the bandwidth ranging from 1.65 to 4.40 GHz and the power ranging from-17.2 to-10.5 dBm.Meanwhile,the input circuit collects the signal voltage of the peak-to-peak value ranging from 54 to 72 m V reflected from the coalrock medium.The UWB radar is arranged closely through the dual Vivaldi antenna being perpendicular to the coal and rock seam.The transmitting antenna sends 7 thorder Gaussian pulse UWB band signal as low as-19 d Bm,while the receiving antenna collects 512-depth return signals at a rate of 30 Gbps.In this way,the precise coal-rock interface location can be estimated through multiplying the propagation delay of pulse reflection and sending signals generated by the apparent difference of dielectric constant in the coal and rock by the electromagnetic wave propagation rate calculated after calibrating the dielectric constant of at the coal-rock site.Moreover,based on changes in the depth of coal seam and dielectric constant,the relationship of coal-rock detection among pulse vertical resolution,detection depth and length of the signal sampling window are established to determine that the length of sampling window is 256 ns with the measuring resolution reaching 4 mm.A waveform gray-scale map is drawn with pulse signal data collected for intuitively distinguishing the coal-rock interface location.To be specific,dark black and bright white in the map are the valley and peak of the signals,respectively,representing the interface locations of two media of coal-rock with great differences in the dielectric constant.In the meantime,the thickness of the coal seam is calculated by the time difference from the valley or the peak to the starting point.In the fully mechanized coal mining face and roadway field test for roof coal mining,the thickness of the coal seam measured with the error less than 20 mm can detect the thickness of the roof coal and the floor coal of the working face in the virgin coal,providing accurate location reference for the automatic horizon control of the shearer.
引文
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[8]文虎,张铎,郑学召,等.基于FDTD的电磁波在煤中传播特性[J].煤炭学报,2017,42(11):2959-2967.WEN Hu,ZHANG Duo,ZHENG Xuezhao,et al.Propagation characteristics of electromagnetic wave based on FDTD in coal[J].Journal of China Coal Society,2017,42(11):2959-2967
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[10]郝建军,孙晓晨.几种透地通信技术的分析与对比[J].湖南科技大学学报(自然科学版),2014,29(1):59-63.HAO Jianjun,SUN Xiaochen.Analysis and comparison of several through-the-earth communication technologies for mining[J].Journal of Hunan University of Science&Technology(Natural Science Edition),2014,29(1):59-63.
[11]唐彤彤,杨维,邵小桃.不规则分层地层中电磁波透地传输的衰减特性[J].煤炭学报,2017,42(7):1912-1918.TANG Tongtong,YANG Wei,SHAO Xiaotao.Transmission attenuation characteristics of electromagnetic wave through irregular layered strata[J].Journal of China Coal Society,2017,42(7):1912-1918.
[12]PEPLINSKI N R,ULABY F T,DOBSON M C.Dielectric properties of soils in the 0.3-1.3-GHz range[J].IEEE Transactions on Geoscience and Remote Sensing,1995,33(3):803-807.
[13]DOBSON M C,ULABY F T,HALLIKAINEN M T,et al.Microwave dielectric behavior of wet soil-Part II:Dielectric mixing models[J].IEEE Transactions on Geoscience and Remote Sensing,1985(1):35-46.
[14]唐彤彤,杨维,邵小桃.基于PSO-GA的Kriging插值法建立透地通信分层地层媒质模型[J].煤炭学报,2016,41(11):2913-2920.TANG Tongtong,YANG Wei,SHAO Xiaotao.Based on the Kriging interpolation method with PSO-GA to establish a layered stratum model for though-the-earth communication[J].Journal of China Coal Society,2016,41(11):2913-2920.
[15]孙红雨,王娜,郭银景,等.透地通信系统研究进展[J].山东科技大学学报:自然科学版,2011,30(3):79-85.SUN Hongyu,WANG Na,GUO Yinjing,et al.Research Progress of Though-the-earth Communication System[J].Journal of Shandong University of Science and Technology:Natural Science,2011,30(3):79-85.
[16]SOJDEHEI J J,WRATHALL P N,DINN D F.Magneto-inductive(MI)communications[A].OCEANS,2001.MTS/IEEE Conference and Exhibition[C].IEEE,2001:513-519.
[17]JACK N,SHENAI K.Magnetic induction IC for wireless communication in RF-impenetrable media[J].IEEE Workshop on Microelectronics and Electron Devices,2007,13(4):47-48.
[18]AKYILDIZ I F,WANG P,SUN Z.Realizing underwater communication through magnetic induction[J].IEEE Communications Magazine,2015,53(11):42-48.
[19]BANSAL R.Near-field magnetic communication[J].IEEE Antennas and Propagation Magazine,2004,46(2):114-115.
[20]SUN Z,AKYILDIZ I F.Optimal deployment for magnetic induction-based wireless networks in challenged environments[J].IEEETransactions on Wireless Communications,2013,12(3):996-1005.
[21]SUN Z,AKYILDIZ I F.Magnetic induction communications for wireless underground sensor networks[J].IEEE Transactions on Antennas and Propagation,2010,58(7):2426-2435.
[22]ZHANG Zhengqing,LIU Erwu,ZHENG Xiaojun,et al.Cooperative magnetic induction based through-the-earth communication[A].IEEE/CIC International Conference on Communications in China[C].IEEE,2014:653-657.
[2]张德,姜崇海,王雪莲,等.探地雷达在薄煤层探测中的应用[J].中国煤田地质,1997(1):76-78.ZHANG De,JIANG Chonghai,WANG Xuelian,et al.Application of GPR in thin coal seam exploration[J].China Coal Field Geology,1997(1):76-78.
[3]李刚.煤层厚度变化的透射槽波探测技术[J].煤矿开采,2016,21(5):11-13,55.LI Gang.Transmission channel wave detection technology for coal seam thickness change[J].Coal Mining,2016,21(5):11-13,55.
[4]吴正飞,韩德品,王程,等.综采工作面薄煤带范围精细综合物探[J].煤矿安全,2014,45(12):68-71.WU Zhengfei,HAN Depin,WANG Cheng,et al.Fine comprehensive geophysical exploration of thin coal belt in comprehensive mining face[J].Coal Mine Safety,2014,45(12):68-71.
[5]梁庆华,吴燕清,宋劲,等.探地雷达在煤巷掘进中超前探测试验研究[J].煤炭科学技术,2014,42(5):91-94.LIANG Qinghua,WU Yanqing,SONG Jin,et al.Experimental study on advanced detection of mine-detecting radar in coal roadway excavation[J].Coal Science and Technology,2014,42(5):91-94.
[6]李力,魏伟,唐汝琪.基于改进S变换的煤岩界面超声反射信号处理[J].煤炭学报,2015,40(11):2579-2586.LI Li,WEI Wei,TANG Ruqi.Ultrasonic reflection signal processing at coal-rock interface based on improved S transform[J].Journal of Coal Science,2015,40(11):2579-2586.
[7]王昕,丁恩杰,胡克想,等.煤岩散射特性对探地雷达探测煤岩界面的影响[J].中国矿业大学学报,2016,45(1):34-41.WANG Xin,DING Enjie,HU Kexiang,et al.Effects of the scattering characteristics of coal and rock on the interface of the groundpenetrating radar to detect coal and rock[J].Journal of China University of Mining Technology,2016,45(1):34-41.
[8]文虎,张铎,郑学召,等.基于FDTD的电磁波在煤中传播特性[J].煤炭学报,2017,42(11):2959-2967.WEN Hu,ZHANG Duo,ZHENG Xuezhao,et al.Propagation characteristics of electromagnetic wave based on FDTD in coal[J].Journal of China Coal Society,2017,42(11):2959-2967
[9]PATRI A,NAYAK A,JAYANTHU S.Wireless communication systems for underground mines-a critical appraisal[J].International Journal of Engineering Trends and Technology,2013,4(7):3149-3153.
[10]郝建军,孙晓晨.几种透地通信技术的分析与对比[J].湖南科技大学学报(自然科学版),2014,29(1):59-63.HAO Jianjun,SUN Xiaochen.Analysis and comparison of several through-the-earth communication technologies for mining[J].Journal of Hunan University of Science&Technology(Natural Science Edition),2014,29(1):59-63.
[11]唐彤彤,杨维,邵小桃.不规则分层地层中电磁波透地传输的衰减特性[J].煤炭学报,2017,42(7):1912-1918.TANG Tongtong,YANG Wei,SHAO Xiaotao.Transmission attenuation characteristics of electromagnetic wave through irregular layered strata[J].Journal of China Coal Society,2017,42(7):1912-1918.
[12]PEPLINSKI N R,ULABY F T,DOBSON M C.Dielectric properties of soils in the 0.3-1.3-GHz range[J].IEEE Transactions on Geoscience and Remote Sensing,1995,33(3):803-807.
[13]DOBSON M C,ULABY F T,HALLIKAINEN M T,et al.Microwave dielectric behavior of wet soil-Part II:Dielectric mixing models[J].IEEE Transactions on Geoscience and Remote Sensing,1985(1):35-46.
[14]唐彤彤,杨维,邵小桃.基于PSO-GA的Kriging插值法建立透地通信分层地层媒质模型[J].煤炭学报,2016,41(11):2913-2920.TANG Tongtong,YANG Wei,SHAO Xiaotao.Based on the Kriging interpolation method with PSO-GA to establish a layered stratum model for though-the-earth communication[J].Journal of China Coal Society,2016,41(11):2913-2920.
[15]孙红雨,王娜,郭银景,等.透地通信系统研究进展[J].山东科技大学学报:自然科学版,2011,30(3):79-85.SUN Hongyu,WANG Na,GUO Yinjing,et al.Research Progress of Though-the-earth Communication System[J].Journal of Shandong University of Science and Technology:Natural Science,2011,30(3):79-85.
[16]SOJDEHEI J J,WRATHALL P N,DINN D F.Magneto-inductive(MI)communications[A].OCEANS,2001.MTS/IEEE Conference and Exhibition[C].IEEE,2001:513-519.
[17]JACK N,SHENAI K.Magnetic induction IC for wireless communication in RF-impenetrable media[J].IEEE Workshop on Microelectronics and Electron Devices,2007,13(4):47-48.
[18]AKYILDIZ I F,WANG P,SUN Z.Realizing underwater communication through magnetic induction[J].IEEE Communications Magazine,2015,53(11):42-48.
[19]BANSAL R.Near-field magnetic communication[J].IEEE Antennas and Propagation Magazine,2004,46(2):114-115.
[20]SUN Z,AKYILDIZ I F.Optimal deployment for magnetic induction-based wireless networks in challenged environments[J].IEEETransactions on Wireless Communications,2013,12(3):996-1005.
[21]SUN Z,AKYILDIZ I F.Magnetic induction communications for wireless underground sensor networks[J].IEEE Transactions on Antennas and Propagation,2010,58(7):2426-2435.
[22]ZHANG Zhengqing,LIU Erwu,ZHENG Xiaojun,et al.Cooperative magnetic induction based through-the-earth communication[A].IEEE/CIC International Conference on Communications in China[C].IEEE,2014:653-657.
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