Navegando por Assunto "Ground penetrating radar"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Investigação de pavimento asfáltico por meio do método geofísico radar de penetração do solo
(Universidade Federal do Pará, 2011) AMARAL, Carolina Narjara Mazzini; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774
Most public paved roads may have some sort of imperfection that leads to unsafe traffic, increased transport costs, and pollution. These problems could be avoided if the defects were identified on the floors before they show up at the surface because in general they begin in the underlying layers of the asphalt coverage. This paper proposes the use of GPR to identify problems in pavements based on numerical simulations of the GPR and on field surveys. Simulation of two physical models has been made: i) pavement in use, in which pipe and the most common defects (voids and infiltration) have been inserted, and ii) recent floors, both above a substrate. The interfaces of the pavement layers and the channeling were easily individualized whereas the imperfections show similar patterns of reflection, differing in the polarity of the signal amplitude and in its attenuation (smaller in the voids and higher in the infiltration). Differently from what occurs in other places, the layer interfaces in recent pavements were more easily identified with the frequency of 400 MHz than with a frequency of 900 MHz because of the conductivity of the products deriving from weathering, which occurs in the Amazon. These responses were used then to investigate two places in the city of Belém (PA): a sector of MauritiTv. which presents recurrent defects on pavement, and a newly paved stretch at Federal University of Pará (UFPA). The first survey identified and mapped defects and permitted to infer their possible causes (water loss from the drainage system) while the latter helped in delineating layers and the contact with the substrate (showing that the thickness of pavement layers differ from the projected ones). The results show how the GPR can be an important tool in maintaining and planning the recovery of paved roads by providing a diagnosis in a fast, safe, and low cost.
Acesso aberto (Open Access)
Investigação geofísica forense e antropológica com o método GPR no cemitério do Tapanã e no cemitério perdido de Mosqueiro (Belém, Pará)
(Universidade Federal do Pará, 2013-03-22) BRASIL, Diogenes Leão; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774
This work was accomplished with ground penetrating radar (GPR), a geophysical method used to investigate the shallow subsurface with high resolution in a non-destructive and noninvasive way. The survey was conducted in two locations in the metropolitan region of Belém, Pará State (Brazil), with 200 and 400 MHz antennas, both in the Tapanã cemetery: the first located in the test site for Controlled Testing of Forensic Geophysics, Environmental and Rescue (FORAMB) and the second one, in a burial zone with concrete cover. Surveys were also conducted in the northwest portion of Mosqueiro Island, across Marajó Bay, with a 400 MHz antenna, where reports of traces of a non-registered cemetery that would have been abandoned for about 80 years and could have been the final destination of cabanos, slaves and indians.These reports led researchers from the Federal University of Pará (UFPA) to visit the site in 1986 to test the veracity of the reports. At FORAMB the monitoring of the three targets that were buried there in 2007 was continued: a human body in a shallow grave 0.8 m deep, a tunnel simulated by a hollow wooden box placed 1 m deep and a box with metal, simulating weapons, deposited at 0.8 m depth. In the burial zone with concrete cover, the survey efforts focused on the effect of the concrete cover.The results obtained in the Tapanã cemetery show the usefulness of GPR in viewing targets under shallow soil cover and saturated clay, typical of the Amazon region, even when it is covered by a layer of concrete. These results reinforce the importance of pooling 2D and 3D data for interpretation of results; the GPR profiles over the concrete covering the bodies in various ages of burial, moreover, show significant variations of the responses, partly observed in other studies. The Mosqueiro results showed that ancient targets in climatic and geological conditions of the Amazon region, do not allow easy detection. It is possible that the remains of the decomposed bodies are not amenable to detection, but the discontinuity of the strata above the burial due to excavation, and the resulting concavity of the collapsed grave infill material may be diagnostic.
Acesso aberto (Open Access)
Investigações ambiental e forense com os métodos geofísicos radar de penetração do solo, polarização induzida e eletrorresistividade no Cemitério do Tapanã, Belém/Pará
(Universidade Federal do Pará, 2010-04-30) CATETE, Clístenes Pamplona; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774
The cemeteries are considered potential sources of underground water contamination. Since the use of geophysics in the mapping of the hydrostatic level (HL) has become a very important tool in the environmental monitoring, it makes possible to verify adequate or inadequate areas for burials in cemeteries. In the other hand, the localization of underground clandestine hollows and tunnels, can be of utility for the Forensic Science. In this work, geophysical methods were applied for mapping the HL in a cemetery and to find buried structures related to the Forensic Science. Ground Penetrating Radar (GPR) was used in the mapping of the HL in the whole Tapanã cemetery, while the resistivity and induced polarization (IP) methods were applied on a test site built in that cemetery for forensic, environmental and resgate related geophysical studies. The results with the GPR showed that the HL depth in the Tapanã cemetery varies from 7 m, at high topographic levels, to 1 m, at low topographic levels. The IP was sensible to the presence of a body buried in a shallow hollow as the clandestine hollows are and showed only fair results for a tunnel. The resistivity was effective for both the buried body and the tunnel, with better definition of the tunnel. The methods gave good results even within the weathering layer rich in clay that normally occurs in the Amazon region.
Acesso aberto (Open Access)
O método GPR aplicado à arqueologia no Sítio PA-ST-42: porto de Santarém, Pará
(Universidade Federal do Pará, 2014-03-06) FURTADO, Carla Patrícia Queiroz; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128