The Lateral Resolution of Three-Dimensional Underground Imaging by Using Amplitude Correlation Synthesis Processing Method

The lateral resolution of the three-dimensional (3D) amplitude correlation synthesis processing (ACSP) method for imaging objects buried underground is studied by computational simulation and experimental measurement. An electromagnetic-induction sound source is employed for radiating a powerful impulsive elastic wave into the ground. Twelve receivers at identical intervals are placed symmetrically to form a cross-shaped array with its center at the sound source. The 12 signals reflected from underground objects are calculated by the 3D ACSP method. Two neighboring objects buried at an identical depth underground are imaged using signals acquired from both the computational simulation and the experimental measurement. The comparison of imaging results derived from different apertures of the array of receivers and different intervals of objects buried underground shows that two objects with a lateral interval of 0.9 m (over 1λ) buried at a depth of 1.5 m (about 2λ) can be imaged separately, using the echo signals of receivers in an array with an aperture of 2.4 m (about 3λ).