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Estudo de materiais rochosos carbonatados localizados nas áreas de Ançã e Souselas
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Advisor(s)
Abstract(s)
Resumo: Apresenta-se uma caracterização de calcários e margas carbonatadas localizadas nas áreas de Souselas e Ançã. Na primeira área o material
rochoso enquadra-se na Formação de São Gião, pertence ao Toarciano, e
corresponde a um conjunto margo-carbonatado. As litologias da segunda
área enquadram-se nos Calcários de Ançã, de idade do Bajociano Inferior.
Na caracterização dos maciços rochosos recorreu-se ao Rock Mass Rating
(RMR). Efetuaram-se ensaios como a determinação da massa volúmica
aparente, porosidade aberta, ensaio de desgaste em meio húmido, dureza,
resistência à carga pontual, resistência à compressão uniaxial, velocidade
de propagação de ultrassons e determinação de módulos de elasticidade dinâmicos. A porosidade das rochas carbonatadas de Souselas e Ançã varia,
respetivamente, entre 7,4%, e 9,5%, e entre 11,1% e 14,3%. Os maciços
rochosos das áreas estudadas são na sua maioria, de acordo com RMR, classificados como de qualidade mediana. Definiram-se as possíveis relações
entre os resultados dos vários ensaios.
Abstract: Astudy of limestone and marly limestone of Jurassic age, located in Souselas and Ançã areas, is carried out. Sousela’s slope is located 8 km North of Coimbra, while Ançã’s Slope is situated 4 km SE of Cantanhede. Sousela’s slope is composed by marly limestone that belongs to São Gião Formation of Toarcian age.Ançã’s Slope presents compact gray limestone with a layer thickness of 2 to 3 m, followed by white compact limestone with a layer thickness of 0.5 to 1 m, containing ammonites. Ançã’s limestone is of Jurassic age and belongs to Lower Bajocian. Rock Mass Rating (RMR) was used to characterize the studied rock masses. Physical and mechanical characterization testssuch as density, open porosity, hardness, durability, point load test, uniaxial compressive strength, and ultrasonic pulse velocity tests were carried out. Dynamic young moduli were also defined. Porosity of carbonated rock from Souselas andAnçã slopes, varies, respectively, between 7.4% and 9.5%, and between 11.1% and 14.3%. Longitudinal sonic pulse velocity (Vp) varies between 1883 m/s and 4554 m/s; and between 4360 and 4842 m/s,for Souselas andAnçã rock material, respectively. According to RMR results, the studied rock slopes are generally classified as fair, with values comprehended between 41 and 60. Possible relationships between the measured parameters were established. A linear and direct relation, with a correlation coefficient value of 0.7, was defined between velocity of longitudinal (Vp) and transversal (Vs) waves; and a correlation coefficient value of 0.5 was stablished between uniaxial compressive strength and velocity of the longitudinal (Vp) values.
Abstract: Astudy of limestone and marly limestone of Jurassic age, located in Souselas and Ançã areas, is carried out. Sousela’s slope is located 8 km North of Coimbra, while Ançã’s Slope is situated 4 km SE of Cantanhede. Sousela’s slope is composed by marly limestone that belongs to São Gião Formation of Toarcian age.Ançã’s Slope presents compact gray limestone with a layer thickness of 2 to 3 m, followed by white compact limestone with a layer thickness of 0.5 to 1 m, containing ammonites. Ançã’s limestone is of Jurassic age and belongs to Lower Bajocian. Rock Mass Rating (RMR) was used to characterize the studied rock masses. Physical and mechanical characterization testssuch as density, open porosity, hardness, durability, point load test, uniaxial compressive strength, and ultrasonic pulse velocity tests were carried out. Dynamic young moduli were also defined. Porosity of carbonated rock from Souselas andAnçã slopes, varies, respectively, between 7.4% and 9.5%, and between 11.1% and 14.3%. Longitudinal sonic pulse velocity (Vp) varies between 1883 m/s and 4554 m/s; and between 4360 and 4842 m/s,for Souselas andAnçã rock material, respectively. According to RMR results, the studied rock slopes are generally classified as fair, with values comprehended between 41 and 60. Possible relationships between the measured parameters were established. A linear and direct relation, with a correlation coefficient value of 0.7, was defined between velocity of longitudinal (Vp) and transversal (Vs) waves; and a correlation coefficient value of 0.5 was stablished between uniaxial compressive strength and velocity of the longitudinal (Vp) values.
Description
Keywords
Caracterização física Caracterização mecânica Calcários Margas Maciços rochosos Physical characterization Mechanical characterization Limestone Marls Rock masses
Citation
Torres, Andrade & Figueiredo 2020, ‘Estudo de materiais rochosos carbonatados localizados nas áreas de Ançã e Souselas’, Comunicações Geológicas, vol. 107, nº 1 (especial), pp. 79-81. https://doi.org/10.34637/yra8-4n98
Publisher
LNEG - Laboratório Nacional de Energia e Geologia