Aplicação de GPR para estimar espessura e disposição lateral de horizontes do solo e do embasamento granítico a sudeste do Campus 2 da Unipampa Campus Caçapava do Sul

Abstract

GPR (Ground Penetrating Radar) has been used as a subsurface research tool in studies of horizontal delineation and lateral arrangement of the rocky basement as targets of interest in several areas. The objective of this study was to delineate the lateral extension of the soil horizons and the granite rock basement, as well as to analyze the soil properties of texture and moisture. The studied area covers approximately 5400 m2 and is located on campus 2 of Unipampa of Caçapava do Sul, which will serve as a base for future buildings. The study area was divided into 12 lines, forming a mesh with 15 m x 15 m ballots, with 7 lines positioned parallel to each 15 m and oriented to the N30 and the others crossing these perpendicularly on the same line spacing but with N300 orientation. Being the N300 lines with a length of 90 m. Lines 1 and 2 oriented to the N30 with length of approximately 75 m, and the other lines N30 with length of 60m. The acquisition system was realized with the common offset arrangement with armored antennas of 80 MHz central frequency, sampling window of 400 ns, frequency of sampling of 512 MHz, spacing between antennas of 0.45 m and spacing between traces of 0.048 m. All sampling parameters were previously analyzed according to the Nyquist sampling theorem. A total of approximately 900 m of radargrams were collected. In order to integrate in-depth depth data, 10 manual drillings were performed with a drill and a drill. Obtaining depth values of the soil layer between values of 0.03 m to 1.27 m. With the integration of the data of probing and GPR, it was possible to calculate the values for the dielectric constant and the speed of the electromagnetic wave in the soil, being these 11.64041 e 0.08793 m.ns-1. The 80 MHz antennas presented excellent reflectors at depths of less than 1 m. The interpreted final geological profile was presented with the organic soil layer with a thickness of 0.5 to 0.6 m. Layer of unconsolidated rock approximately 2 m thick and the top of the granitic basement at depth 4 m.