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为了研究岩溶地区不同风化程度灰岩的地质雷达波形与频谱特征,以图步信至霍林郭勒一级公路为依托,采用SIR-3000型地质雷达在隧道施工期进行了大量的现场测试,从现场测试数据中筛选出从微至强风化程度灰岩的原始文件,利用RADAN后处理软件对筛选文件进行分析,得到了从微至强风化程度灰岩的波形与频谱特征,分析结果表明:对于从微至中风化灰岩,其线测和点测图像反射较弱,无明显的强反射特征,反射频谱能量分布较散,主频突出,其分布范围为80~95 MHz;对于强风化灰岩,其波形及频谱特征与灰岩的含水率有关,当含水率低于40%时,线测和点测图像反射强烈,反射频谱能量分布较散,主频突出,主频的分布范围为42~90 MHz.当含水率大于40%时,线测和点测图像反射均变弱,线测图像中存在信号模糊区,反射频谱能量分布集中,主频突出,主频的分布范围为15~70 MHz,具有明显的低频特征.研究内容能为岩溶地区隧道施工期地质雷达预报的解译判读提供一定的参考.
In order to study the waveform and spectrum characteristics of the geologic radar of limestone with different degrees of weathering in the karst area, a large number of field tests were conducted during the tunnel construction using the SIR-3000 type GPR based on the map to the Hollingular highway. From the field test data, the original documents of the limestone from micro-to-strong weathering degree were screened out and the screening documents were analyzed by using RADAN post-processing software. The waveform and spectral characteristics of the limestone from the micro-to-strong weathering degree were analyzed. For microlite to southeaster limestone, the line and spot images reflect weakly without obvious strong reflection features, the energy distribution of reflection spectrum is scattered and the dominant frequency is prominent, and its distribution range is 80-95 MHz. For strong weathering Limestone, its waveform and spectral characteristics are related to the water content of limestone. When the water content is below 40%, the line and point images are strongly reflected and the energy distribution of the reflection spectrum is scattered with dominant frequencies, and the distribution range of the dominant frequency Is 42-90 MHz.When the water content is more than 40%, the reflectance of the line measurement and the point-measurement image are weakened, the signal blur area exists in the line measurement image, the energy distribution of the reflection spectrum is concentrated, the dominant frequency is prominent, and the distribution range of the frequency is 15 ~ 70 MHz, with obvious Frequency characteristics. Research can provide a reference for the interpretation of the interpretation of ground penetrating radar forecast in tunnel construction in karst region.