蒙特卡洛方法在地质雷达探测地下管道中的应用

地质雷达是一种探测金属和非金属管道的有效方法，传统方法是利用经验电磁波速度计算管道埋深，存在较大误差，且往往无法估算管径或算法繁琐。蒙特卡洛方法是一种随机模拟的地球物理反演手段，从雷达图像中读取一系列反射回波穿行时间和雷达相对于管顶的位置数据，给定合理的电磁波速度、管道埋深和管径3个参数的范围，可以有效地拟合得到速度、埋深和管径。该方法在南京地铁盾构某区段，用来拟合估算地下输油管、自来水管和污水管的埋深及管径，取得了与实际情况较为一致的结果，拟合的电磁波速度符合地下介质情况。

Application of the Monte Carlo method in ground penetrating radar detection of underground pipelines

Ground penetrating radar (GPR) is effective in detecting metal and non-metal pipelines. Traditional methods of calculating the burial depth of pipelines generally use empirical electromagnetic wave velocity, which have large errors and often fail to estimate pipe diameter or have complex calculation algorithm. The Monte Carlo method is a random simulation method in geophysical inversion. By extracting a series of travel time of reflected echo and radar positions relative to pipeline top from GPR images, and determing reasonable ranges of electromagnetic wave velocity, pipeline depth and diameter, this paper effectively obtain the velocity, pipeline depth and diameter values by a fitting method. This method was used to estimate the depth and diameter of petroleum, water and sewage pipelines in a shield section of the Nanjing Metro, and the results were well consistent with the actual values. The fitted electromagnetic wave velocities accorded well with the underground media conditions.