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经过岩土体介质反射回的地质雷达波特征携带了所穿透的岩土体内部的相关信息,其中地质雷达波频谱主频值可以作为判断岩土体结构特征的一个定量指标.以围岩为石英砂岩的公路隧道工程为依托,采用MALA地质雷达配100 MHz屏蔽天线,对隧道掌子面前方的石英砂岩体进行超前地质探测试验,分析典型的Ⅴ级、Ⅳ级和Ⅲ级石英砂岩围岩的雷达波形图图像特征和雷达波在岩体介质中传播的傅里叶频谱特征.通过分析现场试验数据,得出岩体介质的雷达波主频值因自身结构特征和周边环境变化而在一定的敏感频率区间内的规律.对比分析研究结果与工程开挖实际,表明通过分析超前地质探测获得的雷达波傅里叶频谱主频值特征来反演识别围岩结构特征是切实可行的.
Geological radar wave characteristics reflected by geotechnical media carry relevant information inside the geotechnical penetrated, in which the dominant frequency of the geo-radar wave spectrum can be used as a quantitative index to judge the structural characteristics of rock and soil mass. Relying on the MALA ground penetrating radar with a 100 MHz shielding antenna, the geological exploration test of the quartz sandstone body in front of the face of the tunnel is carried out based on the tunnel project of quartz sandstone. The typical grade Ⅴ, grade Ⅳ and grade Ⅲ quartz sandstone are analyzed The characteristics of radar image and the Fourier spectrum characteristics of radar wave propagating in rock media.Based on the analysis of field test data, it is concluded that the dominant frequency of radar wave in rock media varies with its own structural characteristics and the surrounding environment The results of the comparative analysis and the actual engineering excavation indicate that it is feasible to invert the structural characteristics of the surrounding rock by analyzing the dominant frequency value of the radar wave obtained by advanced geological exploration.