Geosynthetics have been used as reinforcement in various applications in geotechnical engineering. This paper presents a study on the use of geosynthetic reinforcement to reduce the consumption of good-quality sub-ballast material in a railway track in the state of Minas Gerais, Brazil. Six test sections on the railway were instrumented and monitored for a period of 2 years. Nonwoven geotextile and a geogrid were used as reinforcement in different positions in the subballast. The results obtained showed that the presence of geosynthetic reinforcement reduced the strains mobilised in the sub-ballast, reduced the breakage of ballast element, and allowed the use of a cheaper alternative material in the sub-ballast construction. The results showed the potential of the use of alternative sub-ballast material reinforced with geosynthetic to reduce the costs of construction and maintenance of railway tracks.

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Sugar cane bagasse is a residue of the sugar-alcohol industry, and its main destination is represented by burning boilers for power generation. The bagasse cogeneration of power produces a sugar cane bagasse ash (SCBA) residue that does not have a useful destination. Ashes are commonly studied as pozzolan in Portland cement production. International Standards indicate the use of pozzolan with up to 50% substitution. In the present work, we investigate the use of SCBA as an addition in Portland cement. For this purpose, Portland cement was prepared by substituting cement with 0, 10, 20, and 30% processed SCBA in volume. The ashes were processed by re-burning and grinding and were then characterized by scanning electron microscopy, Xray diffraction, laser granulometry, X-ray fluorescence spectrometry, the Chapelle method, and pozollanic activity. To evaluate the cement with substitution, we used the mortar recommended by NBR 7215. The mechanical properties of the cements with replacement were analysed through tests of the compressive strength and flexural strength of mortars. The results appear interesting and support the possible use of SCBA in the production of cement from the aspect of mechanical properties evaluated.

Induced vibrations in tailings dams in Brazil became subject to studies after two major accidents in upstream-built structures. These ground vibrations may be responsible for liquefaction triggers and that motivated the development of this paper, which consists in the presentation of a methodology to perform homogeneous vibration monitoring tests along the entire embankment with an initial offline stage that later progressed to an automated process that represents the core object of the paper. Data collected from the initial monitoring enabled analyses of dam stability when correlating vibration levels in the embankment. As a consequence of such analyses, it was possible to parameterize control levels associated to safety criteria. Monitoring methodology, analysis techniques and gains resulting from the use of automated monitoring systems are presented herein. Parameterized control levels regarding the structure under study as well as their association to the stability condition, analysis of liquefaction trigger set for vibration values, advanced analysis of seismographic records and an automated operational vibration control system from monitoring using seismographic stations are shown. The implementation of the automated monitoring system associated to safety control levels allowed a robust diagnosis of eventual structural damages caused by vibrations in dams. That methodology was applied to a dam in operation and permitted evaluation of operation continuity concerning industrial plants and different operations with earthworks equipment on the embankment and its surrounding area.

A barragem de Irapé, localizada no sudeste brasileiro e inaugurada em 2006, representou um marco na engenharia nacional, devido às condições adversas de sua construção, como topografia íngreme e a presença de sulfetos nos maciços de fundação, o que sustentava a hipótese de geração de drenagem ácida de rochas (DAR). Na época, o problema da DAR era pouco conhecido na construção de usinas hidrelétricas e diversos estudos foram conduzidos para controle e minimização dos riscos ambientais e de engenharia do empreendimento. Estes estudos sustentaram medidas inovadoras de engenharia, incluindo o zoneamento do enrocamento, a adoção de geossintéticos impermeabilizantes e a proteção com aditivos das estruturas de con creto. Este trabalho apresenta resumidamente os resultados de uma ampla campanha laboratorial que objetivou complementar os referidos estudos, na tentativa de melhor avaliar o mecanismo de geração ácida sob o con texto da UHE Irapé. Ela consistiu de amostragem, caracterização petrográfica e química das amostras, ensaios estáticos (pH em pasta e NAG) e cinéticos (lixiviação em colunas e em extrator Soxhlet, ensaios de ciclagem). Os resultados demonstraram que não houve geração ácida nos ensaios cinéticos e no ensaio de pH em pasta, levando-se em consideração os tempos e as condições de ensaio. Por outro lado, a presença de sulfetos nas análises petrográficas e os resultados dos ensaios NAG revelaram potencial de geração ácida em algumas das amostras, demonstrando a necessidade de pesquisas adicionais.

The Brazilian standard pertinent to the design and execution of foundations, NBR 6122/2019, establishes that the safety inspection of foundations of a given project must be conducted based on compliance with specified safety factors. Safety factor verification is imperative to meet regulatory requirements; however, it is not enough to guarantee the safety of a foundation. As there is variability in the resistance and solicitation of the piles that make up a foundation, each safety factor value reflects a failure probability. Therefore, it is fictitious that the use of an adequate safety factor value implies the absence of failure risk. Thus, a reliability analysis, applied to a real building with an access ramp whose foundations are composed of precast concrete piles, based on the probabilistic moments, mean, and coefficient of variation, associated with the variability of pile resistance and solicitation, is presented in this article. The values obtained for the safety factors (2.14 and 1.98 for the building and the ramp foundations, respectively) and failure probabilities (1:2,244 and 1:3,131 for the building and the ramp foundations, respectively) implies that the project in question has an acceptable safety level. This article allows us to conclude that a small variation in the reliability index results in a large variation in failure probability; that a greater global safety factor does not necessarily lead to a lower failure probability and it becomes evident that this reliability analysis is a practical way, to manage the uncertainties inherent in foundation design, allowing rational decision making regarding performance.

This paper presents the results of tests with reinforced model walls submitted to different loading conditions. Different types of reinforcement materials and layouts were employed. Stress and displacement measurements were taken during the tests and failure mechanisms were identified. The results obtained showed that the failure mechanism developed depend on the reinforcement load-extension characteristics, adherence between soil and reinforcement and loading type. A good agreement between predicted and observed failure surfaces, using a simple stability analysis method, was also observed for stiff reinforcements.