道路地下空洞探地雷达波场和时频特性

Wave Field and Time-frequency Characteristics of Ground Penetrating Radar for Underground Cavity of Road

根据城市道路地下介质的分布特征和电性参数设计模型,采用时域有限差分法和广义S变换,对道路地下存在的充气空洞、充水空洞、回填不密实、埋藏金属物状态进行探地雷达正演模拟和时频特征提取。结果表明,地下空洞顶界面的反射波同相轴均呈弧形反射形态,但充气空洞的反射波能量强于充水空洞;地下空洞发育区域的中心频率集中在某个低频区间,其余频率成分分布较均匀;埋藏金属物区域出现两簇高幅值能量团,频率分布较分散;回填不密实区域频率未能显示出较明显的规律。最后,通过工程实测验证了数值模拟的可靠性。

According to the distribution characteristics and electrical parameter design model of the underground medium of urban roads,the time-domain finite difference method and generalized S-transform were used to carry out the forward simulation and time-frequency feature extraction for the area of air-filled cavity,water-filled cavity,unconsolidated backfills and buried metal objects under the road.The results show that the event of reflected waves at the top interface of underground cavities is in the shape of arc reflection,but the reflected wave energy of air-filled cavities is stronger than that of water-filled cavities.The central frequency of the area of underground cavity is concentrated in a low frequency range,and the other frequency components are evenly distributed.There will be two high-amplitude energy clusters in the area of the buried metal,and the frequency distribution is scattered.The frequency of the area of the unconsolidated backfill fails to show a obvious pattern.Finally,an engineering case study verified the reliability of numerical simulation.