黄河河道冰层雷达波特征图谱的现场实验研究

2013年-2014年冬季,利用RIS K2型探地雷达在内蒙古头道拐水文站黄河河道断面开展冰层厚度探测试验。试验使用不同频率天线探测冰厚,并与钻孔实测冰厚对比。结果显示200 MHz频率天线可探测到冰下更深部位的状况,并能够识别出冰花层。利用雷达探测图谱中电磁波传播时间和实测冰厚得到盛冰期雷达电磁波在冰内的实际传播速度为16.3cm/ns;而融化期雷达电磁波在冰内的实际传播速度小于15.0cm/ns。雷达探测结果还显示垂直于河道断面方向的冰层厚度分布不均匀。主流区是以热力学生长的颗粒冰和柱状冰为主,最大冰厚约为60cm;而非主流区是以冰花冰为主,最大冰厚约为70cm。另外,雷达图谱也可以确定冰层裂缝的具体位置、走向。

Field experimental study of the characteristics of GPR images of river ice ZHANG Bao-sen1, ZHANG Fang-xiu1, LIU Zi-yang2, HAN Hong-wei3, LI Zhi-jun3

Radar measurement experiments were performed with a RIS K2 at the Toudaoguai Hydrological Station section in the winter of 2013-2014. The experiments detected ice thickness using radar with different frequency antenna and compared the detected thickness with measured thickness by drilling. The results showed the 200-MHz antenna can detect deeper depth below river ice and identify the frazil ice layer. The radar transmission speed in ice was determined based on the propagation time of radar electromagnetic wave and measured ice thickness. The radar transmission speed was about 16.3 cm/ns in the freezing period and less than 15.0 cm/ns in melting period. The GPR images showed that the thickness of the ice layer was not uniform along the section perpendicular to the course of river. In the main flow area between Pile No. 400 and No. 520, the maximum ice thickness was about 60 cm and the ice was mainly made up of granular ice and columnar ice created by thermodynamic growth. In the non-main flow area between Pile No. 520 and No. 740, the maximum ice thickness was about 70 cm and the ice was mainly made up of frazil ice. In addition, The GPR images can be used to locate the position and direction of the ice cracks in ice layer.