Soft ground improvement techniques have evolved substantially in Brazil in recent years. However, their application in soft and very soft clays requires a good understanding of the fundamentals of ground improvement techniques suited to the problem as well as the actual field behavior when implemented on a real scale. This paper describes some of the most widely used ground improvement techniques in the context of very soft clays in Brazil. The techniques described in the paper use prefabricated vertical drains (PVD) such as vacuum preloading; or combine PVD and rigid inclusion, such as CPR grouting; or are purely column-like elements such as piled embankments (including those executed with the deep mixing technique, DSM); or combine column-like elements with the drainage function, such as stone columns and geosynthetic encased columns; or use cementitious binders such as shallow soil mixing. The paper reference condition is a soft clay foundation in which no strengthening is implemented, such as, an embankment with basal reinforcement or soft clay with vertical prefabricated drains, or the use of vacuum preloading to speed up the consolidation rate. The applications of the ground improvement techniques are illustrated by case histories, numerical analyses, or physical models. Different types of measurements are used to evaluate the performance of each technique, including settlements, horizontal displacements, excess pore pressures, embankment applied stresses, stress concentration factors, and clay strength following the ground treatment. The settlement improvement factor β, the ratio between the settlements for untreated and treated conditions, is shown to be a suitable parameter to assess the degree of improvement imposed in the soft foundation by ranking the various methods in increased order of strengthening effect.

Despite extensive research on unsaturated soil behavior in recent decades, the field of transportation engineering still lacks technically and economically feasible methods for identifying expansive soils along roads, particularly in regions with limited laboratory infrastructure that are distant from developed areas in Brazil. This situation is particularly evident in the state of Acre, located in the southwest of the Brazilian Amazon, where the subgrade predominantly consists of fine, plastic soils and faces challenges of limited availability of crushed stone and high precipitation levels. The volumetric variation of expansive soils in Acre has resulted in significant financial losses and has affected the lives of the local population. This paper proposes a simplified method for the preliminary identification of expansive clays, which is based on geotechnical characterization tests that can be performed at local laboratories. The proposed method utilizes the correlation between the plasticity index (PI) and silt/clay content to determine ranges that express the highest probability of occurrence of soils susceptible to shrink-swell behavior. This method was developed by correlating geotechnical parameters of 321 samples from EMBRAPA's SiSolos database with a geotechnical database of 100 local samples.

Recent advancements in railway construction have emphasized environmental sustainability, integrating considerations of environmental impact into the planning and execution of infrastructure projects to reduce costs and mitigate adverse effects. This study investigates the use of steel slag as a sustainable alternative for railway ballast, grounded in shakedown theory. The characterization of the aggregates was performed in accordance with NBR 5564 and AREMA standards, confirming that the material meets most requirements. The mechanical behavior of the ballast was analyzed under cyclic loading conditions, assessing permanent deformation and the material’s ability to achieve stability (shakedown). Triaxial tests with repeated loading simulated real railway conditions, applying vertical stresses up to 600 kPa and confining pressures ranging from 35 to 200 kPa. The results indicate that steel slag aggregates exhibited promising performance, with seven specimens achieving stable deformation levels, characterized by residual deformations of less than 2.5 mm. Notably, these specimens approached deformations on the order of ${10}^{-7}$, indicating stability under cyclic loading. Furthermore, a comparative analysis of shakedown criteria proposed by various authors revealed variations in limits for granular materials, enhancing the understanding of steel slag aggregate behavior. The experimental results were validated through numerical simulations conducted with Systrain software 2.0, which simulated a loading condition of 32.5 tons per axle, confirming the observations with maximum principal stresses ranging from 166 to 184 kPa in the ballast. The analysis showed that steel slag aggregates can withstand stress levels higher than those of granodiorite, reinforcing their viability as a sustainable alternative for railway ballast.

This paper describes the Index and compression properties of Rio de Janeiro sedimentary clays properties and behaviour of ten deposits of soft to medium clays, situated in industrialized and residential areas of Rio de Janeiro City and Rio de Janeiro State. The data reported in this paper is a summary of the geotechnical properties obtained from laboratory and in situ tests carried out under well-defined contour and drainage conditions. The deposits are described in terms of its index properties, stress history, compressibility, consolidation and strength properties.

The main objective of this study is to assess the reuse of naturally old ballast that was removed from an operating railroad. In order to verify the viability of its reuse, laboratory tests were carried out, based on the procedures and parameters established in literature. The reuse of ballast would reduce costs, minimize the disposal of this material and reduce quarry extraction. There are several standards regulations the ballast’s (gravel) properties, such as size, shape, hardness, abrasion resistance and composition to provide better performance of the rail platform, due to the wide variety of materials and environmental conditions to which they are subjected. Ballast specifications are based on the execution of characterization tests and can be divided according to strength properties and geometric properties. Thus, several specifications have been used by different railway organizations around the world to meet the needs of their projects. One test used to analyze ballast quality is the Los Angeles Abrasion, which provides data on resistance to fragmentation. The durability of the ballast depends on the quality of the gravel related to the original rock composition. This is an important parameter that can be associated with railroad maintenance, which is expensive. A series of tests were carried out to evaluate the ballast properties, as well as an analysis of the geometric and mineralogical characteristics of the gravel, and the impact of the variation of these properties in the performance of the ballast. The viability of reusing the ballast removed from an operating road was then evaluated, and it was concluded that the material is still suitable for reusing, although its properties have undergone a few changes, without modifying its main characteristics and functions.

This paper presents a comparison between rain gauge network and weather radar data in Angra dos Reis city, located in the State of Rio de Janeiro (RJ), Brazil. The city has a high incidence of natural disasters, especially associated with heavy rains in densely populated areas. In this work, weather radar data with a spatial resolution of 1 km were obtained from dual-polarimetric S-band radar operated by the Environmental State Institute of Rio de Janeiro (INEA), located in the Guaratiba neighborhood in Rio de Janeiro city, Brazil; the rain gauge measurements were provided by the National Center for Monitoring and Warning of Natural Disasters (CEMADEN), which is composed of a network with 30 rain gauges covering the studied area. The comparison between the two datasets enables the analysis of which radar products better fit the rain gauge network’s accumulated rainfall by quantifying the uncertainties in precipitation estimates at radar pixels where rain gauges are located. The results indicated that radar products generated with the help of regression techniques obtained from the relation between radar reflectivities and rain gauge measurements were a better fit, constituting essential information while dealing with efficient regulation for rainfall monitoring and forecasting to minimize the risks associated with extreme events.