介质含水率与探地雷达电磁波特征参数关系

The Relationship between Soil Water Content and Parameters of Electromagnetic Wave of Ground Penetration Radar

【目的】研究GPR电磁波属性参数与含水率的内在关系,揭示流域范围内土壤水分赋存特征具有重要意义。【方法】利用美国劳雷工业SIR-3000型地质雷达,对不同含水状态风积沙进行GPR探测试验,分析了不同含水率风积沙试样中电磁波传播过程的参数特征,建立了其与含水率的关系模型,并推算介电常数;利用介电常数仪直接测定不同含水率风积沙试样的介电常数,对比基于波速间接所得介电常数,校验了介质含水率与电磁波特征参数关系模型的有效性。【结果】随介质含水率增加,GPR电磁波的双程走时呈非线性增加趋势,波速呈负线性降低趋势;随含水率增加,基于GPR波速间接推算介电常数与介电常数仪直接测定介电常数呈相似增大趋势,相同条件下两类介电常数最大误差约3.6%。【结论】借助GPR电磁波波速与双程走时可以有效评价风积沙水分赋存特征与介电特性。

【Objective】Propagation of electromagnetic wave of ground penetrating radar(GPR)in soil is impacted by soil water content.The purpose of this paper is to study the relationship between property parameters of the electromagnetic wave and soil water content.【Method】We tested the laurel-3000 GPR on an aeolian sand under different water contents.The relationship between parameters of the electromagnetic wave with soil water content was established to calculate the dielectric constant.We validated this relationship against the dielectric constant of the aeolian sand measured directly using a dielectric constant apparatus.【Result】With soil watercontent increasing, the two-way travel time of the electromagnetic wave increased nonlinearly while the wavevelocity decreased linearly. Also, with the soil water content increasing, the dielectric constant calculated indirectlyfrom the wave velocity of GPR was similar to that measured directly using the dielectric constant apparatus, with amaximum error of 3.6%.【Conclusion】All results showed that GPR is effective to evaluate soil moisture contentand dielectric properties of the eolian sand.