隧道壁后注浆缺陷的雷达波场模拟及信息提取

Numerical Simulation and Information Abstracting for Radar Wave of Faults in Shield Tunneling Back-Filled Grouting Layer

摘要:

采用适于有耗介质的完美匹配层(PML)吸收边界条件的二维时域有限差分算法,对隧道壁后注浆缺陷的典型类型进行电磁波传播的数值模拟.模拟结果表明,自由表面的观测场包含着极强的钢筋散射波,影响了目标体反射波的识别.在此基础上,提出了一种新的基于一致性信息相消的钢筋散射波场去除方法,将自由表面观测的总场减去事先计算得到的钢筋散射场,可从强散射背景中恢复并提取出隧道壁后注浆缺陷目标体的反射波,数值计算结果体现出了该方法的有效性和准确性.

Abstract:

Numerical simulations of radar wave performance in typical fault models of shield tunneling back-filled grouting layer were conducted.The simulation algorithm we used was the finite difference time domain solution over a 2D space,with a perfectly matched layer(PML)absorbing boundary conditions for these attenuation models.Simulated results indicate that the wave field observed at free interface consists of strong scattering induced by steel-bars in concrete lining,so it is difficult to recognize the reflection of objects.A new method is proposed for removing the scattering field,and it is named as coincidence information removing method.The scattering field of steer-bars can be calculated in advance.By subtracting the scattering field from total field observed at free interface,reflection of objects could be abstracted.Numerical computing results show that this technique is effective for removing scattering wave.