探地雷达在多年冻土工程地质勘察中的应用效果研究

Study on the Application Effect of Ground-penetrating Radar in Permafrost Engineering Geological Investigation

摘要:

由于融土和冻土之间存在明显的电性差异,使探地雷达成为研究多年冻土的有效手段之一。本文结合工程实例,对探地雷达在青藏高原多年冻土工程地质勘察中的应用效果进行了现场试验研究。分析了探地雷达探测多年冻土的物理前提条件,总结了多年冻土主要地质要素的雷达图像特征和探地雷达在多年冻土工程地质勘察中的实际应用效果。研究表明融土与冻土的雷达图像特征存在明显差异:融土雷达反射波为低频强宽振幅的稀疏波,波形较杂乱;冻土反射波为高频低振幅细密波,波形较为规则;探地雷达可较为准确地划分地层、识别多年冻土上限、确定多年冻土分布范围,但尚不能有效确定多年冻土的含冰量;另外,探地雷达对细颗粒土的探测效果要明显好于粗颗粒土。文章还指出了现场探测和图像解译分析中需要注意的事项和下一步需要研究解决的问题,建议在开展现场探测工作之前先在有钻探资料或天然地质剖面处进行对比试验,搞清测区内主要地层的物性参数,掌握有效波和干扰波的分布规律,从而提高雷达探测结果的准确性和可靠性。

Abstract:

Research purposes: Ground-penetrating radar is one of the important methods used in permafrost engineering geological investigations.Engineering data in addition to theoretical analysis and field tests of ground-penetrating radar in permafrost engineering geological investigations were used in this study,which summarizes the characteristics of the radar image of the main geologic factors of permafrost regions and analyzes the effect of ground-penetrating radar in permafrost engineering geological investigations.In addition,this paper reports the topics for future analysis and fieldwork.The results show that ground-penetrating radar can accurately classify stratum and aid in determination of the permafrost table and the distribution of permafrost;however,this technology cannot effectively determine the ice content in frozen soil.Moreover,the prospecting effect of ground-penetrating radar is more effective in fine-grained soil than that in coarse-grained soil.