基于磁偶极子构造法几何建模的铁管磁异常正演

摘要

Underground ferromagnetic pipe can be magneticed by earth magnetic field,superposition of magneticed field and earth magnetic field produce magnetic abnormal.By pipe geometry modeling and Magnetic dipole reconstruction we can do Magnetic abnormal forward analysis.Initially,approximate cube elements are used to reconstruct pipe geometric model and output volume and center coordinates of elements.Then cube elements are seen as magnetic dipole and magnetic dipole reconstruction is used to forward pipe magnetic abnormal.At last research the influence of Distance-to-Diameter ratio,magnetic inclination,magnetic declination,geomagnetic field and pipeline's susceptibility on pipe magnetic abnormal forward calculation.The results show that:when Distance-to-Diameter ratio is bigger than 6,magnetic abnormal of measurement points on the same sphere are very close and pipe magnetic abnormal is not affected by magnetic inclination,magnetic declination,and pipeline's susceptibility;pipe magnetic abnormal increases linearly with the increase of geomagnetic field.This result can lay a theory foundation for high precision underground pipeline detection equipment.%地下铁磁性金属管线受地球原磁场磁化产生磁场会改变原地磁场分布,而形成地磁异常;通过管道几何建模和磁偶极子构造法对管道磁异常进行正演分析;首先利用近似的立方体单元对管道进行几何建模并输出相应的立方体单元体积和中心坐标;然后将立方体单元近似为磁偶极子,使用磁偶极子构造法进行管道磁异常正演;最后研究了距径比,磁倾角,磁偏角,地球场强,管道材料磁化率对管道磁异常正演的影响;研究结果表明:在6倍距径比外,同一球面上测点磁异常值接近一致,且管道磁异常正演结果不受磁倾角,磁偏角和材料磁化率的影响;随着地磁场强度增大,管道磁异常呈线性增大;研究成果将为自主研发高精度磁异常地下管线探测设备奠定理论基础.