Cavity detection employing advanced geophysical techniques: a case study

摘要

The exact location of subsurface cavities and the estimation of their dimensions is one of the most important problems in planning geotechnical and engineering activities. For this project, geoelectrical and magnetic prospecting has been carried out at the test site of ITABC-CNR, to detect subsurface cavities. The site is located on the same premises as the installations of ITBAC, near Rome. the cavities are located in a tufaceous formation, with average dimensions of 2 * 2 * 1.5 m. They are found at about 1 to 1.5 m beneath the ground surface and they include tombs of the Sabine Necropolis. A 2D data-acquisition technique has been used to reconstruct a 3D subsurface image of the investigated area. The measurements were made in two different square grids, containing two concealed cavities. A smoothness-constrained inversion scheme for the 2D inversion of earth resistivity data and the complex attributes analysis of the magnetic measurements were used. The efficiency and applicability of these advanced geophysical techniques are discussed. They are also checked for possible demerits and they are compared with each other and with other techniques.