| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 121.08 MB | Adobe PDF |
Authors
Abstract(s)
A execução de cartografia em áreas urbanas confronta-se com a permanente reorganização
do meio urbano, quer pelo aparecimento de novas construções quer pela reorganização do
espaço existente, nomeadamente em zonas de reabilitação de edifícios.
Na cartografia geotécnica em particular, a reorganização urbana permite a observação e
realização de escavações, de fundação, abertura de valas, poços e furos de sondagem, que
constituem um grande acervo de dados para a cartografia geotécnica, sendo que a principal
dificuldade está na exposição mínima, temporal e espacial, do terreno natural.
A utilização dos Sistemas de Informação Geográfica (SIG), no desenvolvimento da cartografia
geotécnica veio dar um passo significativo, pelo recurso à utilização de bases de dados
geográficas, novas ferramentas de análise e mais recentemente a utilização de softwares e
plataformas livres.
Desenvolveu-se ao longo deste trabalho metodologias para utilizar dados de plataformas de
informação geográfica livres (Google maps, Bing maps e OpenStreetMap). Estes dados,
devidamente tratados em software livre de código aberto (QGIS), poderão contribuir para se
elaborar cartografia de índole geotécnica. O trabalho propõe a demonstração da ferramenta
abrangendo várias temáticas: delimitação de áreas identificadoras do grau de alteração do
granito, ângulo de atrito, capacidade de carga admissível e mapa de perigosidade (mapa a
duas variáveis, declive e grau de alteração do granito). Outras temáticas poderão vir a ser
tratadas, como por exemplo a delimitação de áreas com o grau de fracturação do maciço
rochoso, parâmetros mecânicos, ou outras derivadas de informação de geologia de engenharia
e/ou geotécnica.
A utilização destas plataformas permite colmatar o limite temporal referido acima, pois
permite em alguns casos, ter acesso a imagens recolhidas durante a execução de trabalhos de
escavação, contendo dados importantes para a caracterização geológica e geotécnica da área
em estudo.
Relativamente à caracterização do grau de alteração do granito, foi numa primeira fase
efetuada através de módulos com ligação à plataforma streetview e numa segunda fase com
observação in situ. Verificou-se que não havia diferenças significativas entre as duas
amostras. Efetuou-se uma análise estatística, utilizando o SPSS versão 25, através do teste t
(t de student) para as amostras emparelhadas das informações recolhidas, verificou-se que não havia diferenças significativas entre a utilização das imagens obtidas pelo Google Street
View e a observação in situ.
Por último, para se obter informação tridimensional, foi gerado o Modelo Digital de Terreno
(MDT), que permitiu posteriormente gerar o mapa de declive. Alguns dos temas foram
sobrepostos ao MDT obtendo-se deste modo uma representação tridimensional desse mesmo
tema. A representação destes mapas poderá ser feita através de num navegador da internet,
permitindo a rotação e translação deste modelo tridimensional.
In urban areas, the cartographic execution is confronted with their permanent reorganization, either by the appearance of new constructions or by the reorganization of existing area, namely in rehabilitation buildings ’areas. Particularly in geotechnical cartography, the urban reorganization allows the observation and realization of excavations, foundations, trenches, drilling sampling wells and holes, which constitute a great data collection for geotechnical cartography, being the main difficulty the minimum temporal and spatial exhibition of the natural land. The use of Geographic Information Systems (GIS) in the geotechnical cartographys’ development has taken a significant step by using geographic databases, new analysis tools and, more recently, the use of free software and platforms. Methodologies for using data from free geographic information platforms (Google maps, Bing maps and OpenStreetMap) were developed throughout this work. These data, properly processed in free open source software (QGIS), may contribute to the elaboration of geotechnical cartography. This work shows the demonstration of the tool covering several themes: delimitation of areas that identify the degree of granite alteration, friction angle, maximum allowable load capacity and hazard map (two-variable map, slope and degree of granite alteration). Other issues may be addressed, such as the delimitation of areas with the degree of fracture of the rock mass, mechanical parameters, or other derived from geology for engineering and/or geotechnical information. The use of these platforms makes it possible to close the time limit mentioned above, as it allows in some cases to have access to images collected during the excavation work, containing important data for the geological and geotechnical characterization of the area under study. Regarding the characterization of the degree of granite alteration, it was initially made through modules connected to the streetview platform and in a second phase with in situ observation. We verified that there were no significant differences between the two samples. We performed a statistical analysis using SPSS version 25 through the t (student's t-test) test for the paired samples of the collected information and found that there were no significant differences between the use of the Google Street View imagery and the in-situ observation. Finally, in order to obtain three-dimensional information, the Digital Terrain Model (DTM) was generated, which later allowed the slope map to be generated. Some of the themes were superimposed on the DTM, thus obtaining a three-dimensional representation of the same theme. These maps can be represented using a web browser, allowing the rotation and translation of this three-dimensional model.
In urban areas, the cartographic execution is confronted with their permanent reorganization, either by the appearance of new constructions or by the reorganization of existing area, namely in rehabilitation buildings ’areas. Particularly in geotechnical cartography, the urban reorganization allows the observation and realization of excavations, foundations, trenches, drilling sampling wells and holes, which constitute a great data collection for geotechnical cartography, being the main difficulty the minimum temporal and spatial exhibition of the natural land. The use of Geographic Information Systems (GIS) in the geotechnical cartographys’ development has taken a significant step by using geographic databases, new analysis tools and, more recently, the use of free software and platforms. Methodologies for using data from free geographic information platforms (Google maps, Bing maps and OpenStreetMap) were developed throughout this work. These data, properly processed in free open source software (QGIS), may contribute to the elaboration of geotechnical cartography. This work shows the demonstration of the tool covering several themes: delimitation of areas that identify the degree of granite alteration, friction angle, maximum allowable load capacity and hazard map (two-variable map, slope and degree of granite alteration). Other issues may be addressed, such as the delimitation of areas with the degree of fracture of the rock mass, mechanical parameters, or other derived from geology for engineering and/or geotechnical information. The use of these platforms makes it possible to close the time limit mentioned above, as it allows in some cases to have access to images collected during the excavation work, containing important data for the geological and geotechnical characterization of the area under study. Regarding the characterization of the degree of granite alteration, it was initially made through modules connected to the streetview platform and in a second phase with in situ observation. We verified that there were no significant differences between the two samples. We performed a statistical analysis using SPSS version 25 through the t (student's t-test) test for the paired samples of the collected information and found that there were no significant differences between the use of the Google Street View imagery and the in-situ observation. Finally, in order to obtain three-dimensional information, the Digital Terrain Model (DTM) was generated, which later allowed the slope map to be generated. Some of the themes were superimposed on the DTM, thus obtaining a three-dimensional representation of the same theme. These maps can be represented using a web browser, allowing the rotation and translation of this three-dimensional model.
Description
Keywords
Cartografia geotécnica - Guarda (Portugal) Sistemas de informação geográfica (SIG) QGIS (Programas de computador)