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- Geostatistical analysis of settlements induced by liquefaction: case study river Lis Alluviums, PortugalPublication . Veiga, Anabela; Mourato, Sandra; Rodrigues, HugoIn the present work the result of the application of geostatistical methods to soil settlement data is presented. The settlements are induced by liquefaction as a result of an earthquake of magnitude 5.5. In the present paper the ArcGIS Geostatistical Analyst software was used, where a number of Kriging methods are available. Geostatistical analysis was performed on two phases: (i) modelling the semivariogram to analyse the surface properties and; (ii) application of a Kriging method. The best adjustment was obtained with a Gaussian model with a first order function trend removal. The settlement values were obtained from the analysis and treatment of results of SPT tests carried out on soils corresponding to alluvial soils in the urban centre of Leiria, Portugal. The results show a significant area where are expected large settlements that can generate significant damages in the building stock and infrastructures.
- Diapir Mudstone Properties, Leiria, PortugalPublication . Veiga, Anabela; Quinta-Ferreira, MárioThe engineering geology study of the Dagorda Formation outcropping in the core of the Parceiros-Leiria diapir, was based on field reconnaissance, on in situ and laboratory tests. The formation is constituted mainly by clay and silt, sometimes with sand, occasionally with gypsum or marls. The engineering geology properties of the fine materials showed large variability depending on their degree of consolidation and water content, ranging from very poor to fair. The presence of soluble minerals can develop dissolution voids. When exposed, for example in excavation surfaces, they tend to deteriorate because of decompression and exposure to the external environment, easily losing strength when wet, which facilitates the failure on slopes or foundations. The presence of soluble minerals (gypsum and rock salt at greater depth) can develop dissolution voids due to circulating water. In depth the variation of the mechanical properties may lead to difficulties in foundation ground, as well as difficulty of concreting piles, due to the escape of concrete between neighboring piles along fissures and dissolution voids. The occurrence of very low strength seams, may constrain the stability of cuttings. The unusual geotechnical behavior of these terrains due to the presence of both clay and soluble minerals must be taken into account. In all engineering works to be carried out on these materials it is recommended to develop a detailed engineering geology study prior to construction, in order to early identify the problems and to define the suitable solutions and construction techniques to be adapted to each case. The construction works must have geotechnical assistance in order to improve the construction operations.
- Characterization of the Dagorda Claystone in Leiria, Portugal, Based on Laboratory TestsPublication . Veiga, A.; Quinta-Ferreira, M.The Hetangian Dagorda claystone Formation occupies the core of a diapir outcropping in part of the city of Leiria, exhibiting a complex geological structure. The geological and geotechnical characterization is presented based in field observation and laboratory tests allowing to conclude that the Dagorda clay soils exhibit an unfavourable behaviour for urban occupation, due to the presence of expansive clay minerals. When partially saturated these soils can lead to cracking of walls and floors, or even to endanger the stability of buildings, if they have not been strengthened to resist to expansive soil. The presence of soluble minerals, mainly gypsum and seldom halite, can allow the formation of voids and eventually the deformation or collapse of the ground. Suitable safety procedures, in order to prevent hazards should be used.
- Sustainability study of limestone quarry waste into value-added products: PCC and GCCPublication . Monteiro, S. M. C. S.; Jorge, Muanassa; Heleno, M. L.; Oliveira, N. S.; Alves, M. L.; Veiga, A.; Silva, A.Calcium carbonate can be obtained naturally from limestone, chalk, marble, and other sedimentary rock forms. Ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) are two materials that can be produced from natural calcium carbonate. The future of GCC and PCC is promising since they are linked to industries with high demand, such as packaging, building & construction, transportation, and industrial applications, with an expected compound annual growth rate higher than 4% until 2027. This research focuses on the production of GCC and PCC through a comparative analysis that identifies the macro conditions that become advantageous to produce and commercialising PCC in a quarry context. This allows a valorisation of the limestone waste resulting from the extraction operations, converting it into by-products of the process. Not all existing limestone quarries in the Serra de Aire e Candeeiros region are suitable sources of raw material to produce PCC. The five extraction poles were identified with the potential for extracting suitable raw materials, associated with several companies dedicated to the extraction operation in these quarries.
- Qualitative analysis of the limestone waste potential from the Serra de Aire e Candeeiros quarriesPublication . Monteiro, S. M. C. S.; Jorge, Muanassa; Oliveira, N. S.; Alves, M.L.; Veiga, A.; Silva, A.The mountains of Aires and Candeeiros are part of the Maciço Calcário Estremenho where the landscape is predominantly made up of limestone. The limestone explored in the region has been the driver of social and cultural development, contributing significantly to the local economy. This emerging concern has motivated public and private organisations to develop solutions to improve the sector's sustainability. The present work aims to evaluate the limestone waste potential to produce precipitated (PCC) and ground (GCC) calcium carbonate in the region by surveying the local extraction industries that fulfil the defined minimum requirements to produce high quality PCC and GCC. The results allowed to stablish an estimate of the amount of waste resulting from the extraction process. The conversion of these wastes into PCC or GCC constitutes a possibility of recovery into by-products, allowing use in noble and profitable applications and contributing to the circular economy and the sustainability of the sector.