本文選題：地電阻率 + 交流觀測方法��； 參考：《中國地震局地殼應力研究所》2015年碩士論文

【摘要】：針對目前地震地電阻率直流觀測中面臨的地鐵、輕軌等電磁干擾問題,開展地電阻率交流觀測方法的研究。重點對地電阻率交流觀測中涉及到的關鍵技術(shù)問題進行了研究,總結(jié)了地電阻率交流觀測方法中的信號檢測方法和地電阻率交流觀測系統(tǒng)的關鍵技術(shù)指標要求。地電阻率交流觀測方法基于電法勘探和地電阻率直流觀測的理論基礎,由于交流信號頻率在10-3Hz-103Hz時,可以近似認為其仍然遵循歐姆定律,這時的低頻交流電場為似穩(wěn)電場。因此地電阻率交流觀測方法在此頻段范圍內(nèi)可以采用與直流觀測相同的理論基礎。首先,對地電阻率交流觀測的實際工作過程進行了數(shù)值模擬,用單一頻率的正弦信號作為供電信號,高斯信號作為噪聲信號,接收裝置在測量極得到的輸入信號為二者的疊加信號。常用的信號檢測方法有帶通濾波器法、相關檢測法和頻譜分析法,利用數(shù)值方法模擬三種方法在不同信噪比、采樣率和采樣時間條件下三種信號檢測方法對輸入信號的檢測精度。通過對比分析檢測結(jié)果,并結(jié)合三種方法在實際系統(tǒng)中實現(xiàn)的難易程度,給出了對疊加高斯白噪聲的己知頻率正弦信號進行信號檢測的最適宜的方法——頻譜分析法。其次,使用多通道數(shù)據(jù)采集器對北京西集臺、天津青光臺、遼寧新城子臺和江蘇江寧臺四個受地鐵干擾嚴重的臺站的場地環(huán)境進行24小時左右的測試,通過對測試數(shù)據(jù)的時、頻域特征分析,總結(jié)了地鐵干擾信號的特征：地鐵干擾信號的周期主要在120s-180s范圍內(nèi)；干擾信號幅度在10mV～30mV左右,特別嚴重的可以達到90mV左右；由于地鐵干擾引起的地電阻率測量時的信噪比下降約20-30dB。第三,根據(jù)地鐵干擾的特征分析,使用頻譜分析法作為信號檢測方法以地鐵干擾信號作為噪聲信號,仿真地電阻率交流觀測方法的信號檢測結(jié)果。結(jié)果顯示,供電信號頻率在0.5Hz以上,當信噪比為0dB,采樣時間滿足400s時,或信噪比為10dB,采樣時間滿足200s時,得到的相對誤差能夠滿足地電阻率觀測規(guī)范的要求。由此,驗證了地電阻率交流觀測方法的可行性。最后,在上述研究的基礎上,給出了地電阻率交流觀測系統(tǒng)的主要技術(shù)指標要求。以期能夠為地電阻率交流觀測系統(tǒng)的研制提供理論參考和技術(shù)依據(jù)。
[Abstract]:In view of the problems of subway, light rail and other electromagnetic interference in the current observation of seismic ground resistivity, the study of the method of earth resistivity AC observation is carried out. The key technical problems involved in the earth resistivity exchange observation are studied, and the signal detection method and the ground resistivity intersection method are summarized. The key technical index of the flow observation system requires that the ground resistivity exchange observation method is based on the theoretical basis of the electric exploration and the direct current observation of the earth resistivity. Because the frequency of the AC signal is at 10-3Hz-103Hz, it can be considered that it still follows the Ohm law, and the low frequency alternating current field is a quasi stable electric field. In the range of this frequency band, we can use the same theoretical basis as the direct current observation. First, the actual working process of the earth resistivity AC observation is numerically simulated. The sinusoidal signal of a single frequency is used as the power supply signal, the Gauss signal is used as the noise signal and the receiving device has the superimposed signal of the input signal of two. The common signal detection methods include bandpass filter, correlation detection and spectrum analysis, and use numerical methods to simulate the detection accuracy of the three methods on the input signals of three signal detection methods under different signal to noise ratio, sampling rate and sampling time. By comparing and analyzing the test results, and combining the three methods in the actual system, the results are compared and analyzed. The most suitable method for signal detection of the known frequency sinusoidal signal superimposed on Gauss white noise is given. Secondly, four stations of Beijing West set platform, Tianjin green platform, Liaoning Xincheng sub platform and Jiangsu Jiangning platform are used to use multi channel data collector. After 24 hours of testing, the characteristics of the subway interference signal are summarized through the analysis of the test data and frequency domain characteristics: the cycle of the subway interference signal is mainly in the range of 120s-180s; the amplitude of the interference signal is about 10mV to 30mV, and it can reach about 90mV. The signal to noise ratio of the quantity is reduced by about 20-30dB. third. According to the analysis of the characteristics of the subway interference, the frequency spectrum analysis is used as the signal detection method, and the subway interference signal is used as the noise signal to simulate the signal detection results of the ground resistivity AC observation method. The result shows that the frequency of the power supply signal is above 0.5Hz, when the signal to noise ratio is 0dB, the sampling time is full. At the time of 400s, or when the signal to noise ratio is 10dB and the sampling time satisfies 200s, the relative error can meet the requirements of the earth resistivity observation specification. Thus, the feasibility of the earth resistivity AC observation method is verified. Finally, the main technical requirements of the earth resistivity observation system are given on the basis of the above research. It provides theoretical reference and technical basis for the development of ground resistivity observation system.
【學位授予單位】：中國地震局地殼應力研究所
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P315.722

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相關期刊論文 前1條

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本文編號：2072350