(中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長(zhǎng)沙 410083)
摘 要: 為了更好地模擬探地雷達(dá)(GPR)波在地下真實(shí)介質(zhì)中的傳播特征，首先采用隨機(jī)過(guò)程的譜分解理論和混合型自相關(guān)函數(shù)理論構(gòu)造隨機(jī)介質(zhì)模型，然后詳細(xì)介紹無(wú)單元法在GPR正演模擬中的應(yīng)用。在此基礎(chǔ)上，利用無(wú)單元法對(duì)2個(gè)典型的隨機(jī)介質(zhì)模型進(jìn)行正演計(jì)算，分析隨機(jī)介質(zhì)模型中GPR波的傳播特征，并與均勻介質(zhì)模型進(jìn)行對(duì)比。模擬結(jié)果表明：隨機(jī)介質(zhì)模型理論能靈活、有效地描述地下實(shí)際介質(zhì)的分布，具有適應(yīng)性強(qiáng)、使用方便、靈活的優(yōu)點(diǎn)；與均勻介質(zhì)中GPR波的傳播相比，隨機(jī)介質(zhì)中GPR波的傳播由于受到小尺度異常的影響散射現(xiàn)象非常強(qiáng)烈，波形發(fā)生扭曲；隨機(jī)介質(zhì)中異常體產(chǎn)生的反射波形非常粗糙，甚至發(fā)生同相軸不連續(xù)的現(xiàn)象，并且反射波能量較弱，隨機(jī)介質(zhì)模型模擬所得的正演剖面與實(shí)測(cè)剖面更相符，更有利于指導(dǎo)雷達(dá)剖面的數(shù)據(jù)解譯。
關(guān)鍵字: 探地雷達(dá)；無(wú)單元法；隨機(jī)介質(zhì)模型
（School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:In order to better simulate the propagation characteristics of ground penetrating radar (GPR) waves in the real underground medium, the random media models were constructed according to the theory of spectral factorization in stochastic processes and mixed autocorrelation function. Application of element free method in GPR forward modeling was introduced in detail. On this basis, forward modeling was carried out on two typical random media models by the element free method and the propagation characteristics of GPR wave in random media models were analyzed, and compared with those in homogeneous media models. The modeling results show that the theory of model in random media can flexibly and effectively describe the actual underground medium, with the advantage of strong adaptability, easiness and flexibility. Compared with the GPR wave propagation in homogeneous medium, GPR wave propagation in random medium has strong scattering phenomenon and the waveform is distorted due to the impact of small-scale anomalies; the reflection waveform generated by anomaly in random medium is very rough and has phase axis discontinuous phenomenon and the wave energy is weak. Forward section of random medium models is more consistent with the measured profiles and is more conducive to the interpretation of the radar profile data.
Key words: ground penetrating radar; element free method; random medium model
