论文部分内容阅读
地质雷达(GPR)法是以电磁波在岩土体介质中的反射和衰减,通过电磁波回波信号反映灰岩隧洞中岩体结构面空间位置及其填充物。建立单条裂隙、双条裂隙和交叉裂隙及其空间位置的二维地电模型,设置结构面中的填充物为空气、泥土、水;以FDTD法正演模拟并对比分析其图像特征。结论如下:填充物对结构面的判据具有较大影响,水对电磁波的强烈吸收作用导致图像成像特征复杂,多次反射波规律性较强;结构性的探测取决于介质介电常数的差异,且近掌子面的结构面对电磁波的反射和吸收形成多次波干扰深部结构面的成像。FDTD正演结果对地质预报的判断提供科学依据和指导作用。
The GPR method is based on the reflection and attenuation of electromagnetic waves in rock and soil media. The electromagnetic wave echo signal reflects the spatial position of rock mass structural plane and its filling in the limestone tunnel. The two-dimensional geoelectric model of single fracture, double fracture and cross fracture and their spatial location is established. The fillings in the structural plane are set as air, soil and water. The FDTD method is used to simulate and analyze the image features. The conclusions are as follows: The filler has a great influence on the criterion of the structural plane. The strong absorption of water by electromagnetic wave leads to the complex imaging features and the regularity of multiple reflected waves. The structural detection depends on the difference of dielectric permittivity , And the structure near the face of the face of the electromagnetic wave reflection and absorption to form a multi-wave interference deep structure of the surface imaging. The results of FDTD forward provide scientific basis and guidance for the judgment of geological forecasting.