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地质雷达技术在公路隧道工程中得到了广泛的应用。作为一种高效,先进的物探方法,探地雷达能够对隧道围岩进行快速扫描,获得形象的探测图形,加上其具有探测精度高,测线范围易调整,工作效率高等优势,成为公路隧道地质超前预报的最主要方法之一。然而公路隧道中的黄土隧道,由于黄土的特殊工程性质,如其孔隙比大,无明显层理,不均匀致密或均匀疏松特性,使得利用电磁波反射原理的方法会出现预报距离短,反射特征弱构造难以识别等问题。本文以陕西黄陵至延安高速公路扩能工程中黄土隧道地质超前预报工作中采集的地质雷达数据为基础,通过预报与实际开挖的比对,总结经验优化了黄土隧道地质雷达预报中的相关参数和分析了影响因素,并利用希尔伯特变换的技术方法对前方地质异常情况及岩性变化进行识别,以及提出基于黄土隧道的频谱特征的辅助分析方法。
Geological radar technology has been widely used in highway tunnel engineering. As an efficient and advanced geophysical prospecting method, GPR can rapidly scan the surrounding rock of the tunnel and obtain the image of the exploration pattern. With the advantages of high detection accuracy, easy measurement range adjustment and high work efficiency, GPR becomes a road tunnel Geological forecast one of the most advanced way. However, due to the special engineering properties of loess, the loess tunnel in highway tunnel, if its porosity ratio is large, there is no obvious bedding, uneven or even loosening characteristics, the method using electromagnetic wave reflection principle will have short forecasting distance and weak reflecting structure Difficult to identify and other issues. Based on the data collected from geological radar in the advanced geological forecasting of loess tunnel in the expansion project of Huangling-Yan’an Expressway in Shaanxi Province, the paper compares the prediction with the actual excavation and sums up the experience to optimize the correlation of the prediction of the geological radar in the loess tunnel Parameters and analyzed the influencing factors. The Hilbert transformation technique was used to identify the anomalous geological anomalies and lithology changes in the front and to propose an auxiliary analysis method based on the spectral features of the loess tunnel.