Resumo em Inglês:

Abstract Geosynthetics are construction materials that can assume different functions in geotechnical engineering and environmental protection works, such as drainage, filtration, reinforcement, protection and as barriers. They are easy to install, to transport to remote areas and provide engineering solutions that impacts less the environment. This paper presents and discusses the use of these materials in environmental protection works, as well as sustainable solutions using different types of geosynthetics and combinations between them and alternative construction materials such as scrap tires and plastics. Applications in waste disposal, drainage, soil reinforcement, etc. are described and discussed. The use of sustainable geosynthetics such as biodegradable mats for erosion protection and geosynthetics manufactured from recycled plastics and scrap tires is also discussed as well as solutions incorporating geosynthetics to minimize the consequences of climate change. The results from experimental studies and case-histories monitoring presented show that geosynthetics can make a significant contribution to environmental preservation and protection, especially in view of the future consequences of the increasing frequency of extreme events caused by climate change.

Resumo em Inglês:

Abstract The demand for tunnels in densely populated urban areas is growing rapidly to address mobility challenges. Mechanized tunneling is widely adopted in urban environments due to its high productivity and the relatively small ground deformations it induces. However, urban tunneling is highly complex because of the typically shallow depths and interactions with aboveground structures. Therefore, accurately predicting ground deformations induced by mechanized tunneling at the design stage is crucial for assessing potential building damage. To investigate these deformations, a series of centrifuge tunnel tests have been conducted at academic institutions such as the Universities of Cambridge and Nottingham to study the behavior of shallow mechanized tunnels in cohesionless soil. These tests serve as excellent benchmarks for numerical model calibration. Once calibrated to replicate centrifuge test results, numerical models can efficiently analyze a wide range of scenarios at a fraction of the time and cost. This paper investigates ground deformations induced by shallow tunneling in cohesionless soil using numerical models calibrated against selected centrifuge tunnel tests, which encompass varying tunnel diameters, depths, and sand relative densities. The numerical modeling results presented in this paper provide extensive insights into tunnel behavior, illustrating how tunnels respond to different relative densities and depths under tunnel volume losses of up to 5%, approaching failure conditions. Additionally, a comprehensive analysis of ground deformations caused by shallow tunnels in sandy soils and their potential impact on buildings is presented.

Resumo em Inglês:

Abstract Climate change is driving non-stationary rainfall patterns, intensifying both the frequency and magnitude of extreme precipitation events, which pose significant risks to earthen embankments. Traditional Intensity-Duration-Frequency (IDF) curves, based on stationary climate assumptions, often underestimate future hydrological loads. This study investigates the stability of embankments with and without geocomposite drainage layers under both stationary and non-stationary IDF scenarios, focusing on return periods of 10, 30, 50, and 100 years. Bengaluru, India, a monsoon-affected urban region, serves as the case study, with future rainfall projections derived from the CMIP6 SSP5-8.5 scenario to represent high-emission pathways. Numerical simulations reveal that unreinforced embankments under non-stationary conditions experience rapid pore-water pressure accumulation and a significant drop in Factor of Safety (FOS), reaching critical saturation in as little as 12 hours for 50-year return events. In contrast, geocomposite-reinforced embankments exhibit improved drainage, delayed saturation, and maintain FOS above 1.5 under stationary scenarios, and up to 18 hours of stability in the 100-year non-stationary case.

Resumo em Inglês:

Abstract Point load strength index (PLSI) and slake durability index (SDI) are two important indices of rocks used to evaluate strength and durability for various engineering applications. This research investigates these two indices in sandstones from the Amile formation coupled with petrography, aiming to determine the strength and durability of rock, and test for correlations among mineral constituents, texture, PLSI, and SDI to develop empirical relationships among them. The study provides insights into the geotechnical properties of an important geological formation in the Lesser Himalayan Zone, contributing valuable data for infrastructure development. The methodology involved field sampling, petrographic analysis of thin sections, SDI testing over two cycles, and PLSI testing on irregular lump samples. Correlations between SDI, PLSI, water absorption, packing density, and packing proximity were statistically analyzed. Quarztose sandstones have extremely high durability (SDI: 99.17–99.78%), very strong to extremely strong compressive strength (PLSI: 5.94–14.81 MPa), and low water absorption values (WAV: 0–2.17%). Very high positive correlations were found between SDI and PLSI with R2 =0.804. Based on this correlation, future research can use the equation SDI = 0.0712PLSI + 98.727 to estimate durability from strength for similar sandstones, saving time and resources.

Resumo em Inglês:

Abstract The paper studies the effect of sample reconstitution for three commonly employed procedures, namely static compaction and standard and modified moist tamping methods, in the context of laboratory testing of mine tailing materials. The effect of initial water content and compaction energy on the resulting densities and uniformity of the samples are examined. Equivalencies between different reconstitution methods were established to attain a given target density. Then, the effect of the resulting fabric was investigated by means of isotopically consolidated undrained triaxial tests, on samples prepared with similar densities and water contents but with different reconstitution techniques. The results showed that all reconstitution techniques studied produced samples with acceptable uniformity and good repeatability. Although similar results were obtained across the different methods, the modified moist tamping technique yielded slightly higher undrained peak strengths and exhibited a more pronounced hardening behavior upon reaching the critical state line compared to the static compaction method. In contrast, the moist tamping and static compaction methods produced comparable responses in loose specimens. These results suggest that dynamic and static reconstitution methods may create subtle differences in the fabric of the samples, influencing their behavior under shearing.

Resumo em Inglês:

Abstract Downhole Seismic Testing (DST) is utilized for estimating low-strain shear damping ratio (ηs). Estimates of low strain ηs values are very important for predicting and assessing ground amplification during earthquakes. The low strain ηs estimates also provide for a reference of laboratory tests such as the resonant column test. The Spectral Ratio Technique (SRT) is one of the most utilized analysis techniques for processing seismic data to obtain ηs. The SRT is applied in the frequency domain where the spectral ratio of two data sets and relative arrival times are calculated to obtain the quality factor. The quality factor is inversely proportional to the damping ratio. One of the limitations of the SRT is that it doesn’t account for the raypaths of the source waves. In DST the raypaths are of particular importance due to the fact the source waves will refract as they travel from the surface down to the seismic receiver. This paper outlines a technique, so-called FMDSM-SRT, which facilitates adjusting estimated SRT absorption DST values so that source wave raypaths are accounted for. It is of paramount importance to first implement newly optimal estimation algorithms on extensive test bed simulations prior to processing real data sets. This paper outlines the results from processing a challenging test bed simulation with the FMDSM-SRT algorithm.

Resumo em Inglês:

Abstract The application of loading tests allows us to evaluate the behavior of shallow foundations under real conditions. This article addresses the application of a constitutive model based on Mohr-Coulomb with a cap failure criterion that simulates the compaction of the material and limits its shear strength to describe the behavior of a footing resting on tropical climate soil composed of silt-clay sand. The foundation was tested in terms of axial compression through a static and slowly maintained loading test (SML) until its failure was characterized by significant settlement. A two-dimensional axisymmetric finite element numerical model was used to process the numerical analyses. The numerical model used was able to simulate with high similarity the load-settlement behavior of the footing tested in the loading test, under different water content conditions and preload imposed in the field tests. Additionally, the experimental results facilitated the successful guidance of the numerical analyses, providing parameters to safely analyze similar foundations under other conditions.

Resumo em Inglês:

Abstract This article aims to evaluate the behavior of piled rafts and pile groups subject to the presence of defective piles. To simulate the defect, it was considered that a foundation pile is shorter than projected. Seven static load tests performed in 2011 in the city of João Pessoa, in north-east Brazil, were used as the basis of analysis. These load tests were performed on an isolated raft, in 3 piled rafts and in 3 pile groups. In this study, the ELPLA® software, based on a hyperbolic iterative model, was used. Initially, modeling was performed for the original situations with intact foundations, and the results were compared with previous experimental results. Afterwards, numerical modeling was performed considering four defect levels, which correspond to a decrease in the pile length. According to the results obtained, it could be observed that, due to the presence of the defect, there was a reduction in the stiffness and load capacities of all the foundations analyzed, the occurrence of differential settlements in the foundations, and an increase in the load absorbed by the raft in the piled rafts.

Resumo em Inglês:

Abstract The collection and treatment of water are crucial to ensure the provision of safe drinking water for the population. Raw water is treated using physical and chemical processes to produce treated water for distribution to cities, but the processes also generate waste. The waste from Water Treatment Plants (WTP) is known as WTP sludge. Disposing of WTP sludge in an environmentally friendly manner is crucial. In order to minimize the environmental impact, waterproof barriers are designed in landfills to prevent the contamination of underground water resources provoked by the percolation of generated liquids. This study assessed the geotechnical feasibility of using WTP sludge as a waterproofing material in landfills. The benefits of this process include a decrease in soil extraction from quarries and the environmentally sound disposal of waste. The approach is based on the growing demand for sustainable practices in the treatment and disposal of waste, while also seeking a technical alternative to partially replace soil in geotechnical structures, aiming for resource conservation. The study characterized the sludge from the WTP and conducted tests on compaction, hydraulic conductivity, and oedometric consolidation. Two different fractions of the soil-sludge mixture (2.5% and 5%) were used, with moisture contents ranging from 17.62 to 46.71%. The results showed that the addition of sludge either maintained (2.5%) or improved (5%) the permeability characteristics of the residual soil under study. In optimal conditions, the permeability was approximately 10-9 m/s, which renders it suitable for use in waterproofing layers for landfills.

Resumo em Inglês:

Abstract During operation, the ballast is subjected to a gradual breakage process that causes clogging of the substructure. Intervention periods on the ballast layer generate high costs that impact the long-term competitiveness of railways. In this context, this work aims to evaluate the geomechanical behavior of reinforced ballast, assessing the effect of reinforcement and stiffness provided by the addition of geogrids. Using 3D printing, the two reinforcement elements were manufactured with PETG and PLA polymers to represent the commercial geogrids Basetrac Grid PET40 and PET65, respectively. Long-term cyclic triaxial tests were used to evaluate the geomechanical behavior of the ballast. The results show that the PLA polymer was more efficient in reducing the deformability of the ballast. Long-term tests also demonstrated that granular materials tend to stabilize plastic deformations, which were not achieved under the stress level and loading frequency adopted in this research, even with the inclusion of geogrids. The low degree of grain breakage shows that the use of cubic particles, together with a well-graded distribution, helps to reduce aggregate degradation in the ballast layer. However, the high confinement levels used in the triaxial tests may have reduced the effect achieved by the reinforcement element. Factors associated with the model geogrids, such as high stiffness, low flexibility, and reduced aperture, also influenced the interaction with the aggregates.

Resumo em Inglês:

Abstract Helical piles are steel elements consisting of one or more helices placed along a central shaft and installed in the ground through rotation. This study describes a field investigation of the behavior of a helical pile prototype subjected to cyclic tensile loads in a site composed of pure sand layers. During the investigation, the helical pile prototype featured three helices and was equipped with electrical resistance strain gauges at three different sections along the shaft. Two cyclic tensile load tests were conducted during the investigation using quasi-static (low-frequency) cyclic loadings. In each test, cyclic loads were applied in four distinct stages. The maximum load reached in each stage was the same in both load tests. However, the cyclic amplitude between stages increased in one load test and kept constant in the other. A static load test was performed immediately after unloading one of the cyclic tests to evaluate the influence of the cycles on the static load capacity. The results revealed that the helix closest to the pile tip contributed the most to the total axial load capacity. Proportionally, the tip helix had the highest contribution among all the helices from the beginning of the test. The mode of load increment application influenced the pile response. Increasing cyclic loads between stages led to an increase in the proportion of the load mobilized at the tip helix and a decrease in the proportion mobilized at the upper helices.

Resumo em Inglês:

Abstract This research aims to study the engineering properties of silty soil reinforced with plastic waste fiber (PWF) extruded from water plastic bottles. Other reinforced soil samples have been treated with cement, except for control samples (untreated soil samples). Curing time, length and percentage of fiber are the variables studied in this research. Lab testing results show that adding plastic waste fiber to the silty soil helps to increase the unconfined compressive strength, indirect tensile strength and punching-tensile strength. The results of soil samples treated with 4% cement show that all strength values have increased significantly. These properties also increase with the increase in the curing time. The increase in strength values of natural soil samples compared with cement-treated samples was (91.7 kPa to 1800 kPa), (6.1 kPa to 312 kPa) and (12 kPa to 371 kPa) for the unconfined compressive, indirect tensile and punching-tensile strength for 28 days of curing time. Regarding the effect of wetting-drying cycles on the strength properties, the results show that the natural soil samples fall apart immediately after being soaked in water. However, the results for samples reinforced with plastic waste fiber, treated with 4% cement and cured for 28 days show that the unconfined compressive, indirect tensile and punching-tensile strength decrease with the wetting-drying cycle from (2500 kPa to 1000 kPa), (435 kPa to 189 kPa) and (580 kPa to 448 kPa), respectively.

Resumo em Inglês:

Abstract In Brazil alone, 12.23 million tires were manufactured in the first quarter of 2024. The inadequate disposal of rubber waste from scrap tires is a globally recognized problem. The incorporation of this solid waste into geotechnical projects can serve to mitigate the environmental impact of its disposal. This paper presents complementary results previously published by Abrantes et al. (2025). This first publication dealt with the following procedures applied to the soil and soil-rubber mixtures: specimen preparation, characterization, standard compaction tests and compaction tests with damping ratio measurement, CIU Triaxial tests and Dynamic Triaxial tests. The current publication (Part 2) presents results and discussions about the following tests performed in soil and soil-rubber mixtures: oedometer tests (consolidation and elastic parameters), oedometer tests (permeability) and direct shear tests (strength parameters). The tests were conducted with pure soil and with soil-rubber mixtures in proportions of 2.5%, 5.0%, 7.5%, 10.0%, 12.5%, and 15.0% of rubber weight in relation to the weight of the pure soil. Based on present study, the rubber from shredded scrap tires can be used in applications such as: a) compacted embankments; b) soil walls reinforced with geosynthetics. Nonetheless the use of rubber mixed with soil is not recommended in clay liners for sanitary landfills.

Resumo em Inglês:

Abstract Preloading with vertical drains is a well-proven ground improvement technique suitable for soft clay deposits. This technique involves installing vertical drains that cause soil remolding in the immediate vicinity of its surface, creating a disturbed zone known as the smear zone. This study aims to investigate the impact of overburden stress on the characteristics of the smear zone. Very often, the vertical drains penetrate to depths up to 20 m. In such situations, the soil experiences varying stresses, leading to different responses to the drain-induced soil disturbances. Very few studies have investigated how overburden stress affects the smear zone. Through a series of experiments encompassing vertical and radial consolidation tests, along with vane shear tests, this paper evaluates the variation in shear strength and consolidation properties within the smear zone, simulating different depths. Employing three overburden pressure intensities (25 kPa, 50 kPa, 100 kPa, equivalent to depths of about 4 m, 8 m and 16 m), the study establishes that the remolding effect intensifies with depth. Furthermore, it demonstrates the influential role of the smear zone on the undrained shear strength properties of the improved ground, highlighting its variability based on overburden stress.

Resumo em Inglês:

Abstract Accurate quantification of calcium carbonate (CaCO3) in soil is critical for geoenvironmental engineering, influencing soil stabilization, carbon sequestration, and climate-resilient design. This study compares four commonly used analytical methods—Loss on Ignition (LoI), Total Inorganic Carbon (TIC), X-Ray Diffraction (XRD), and a Calcium Carbonate Analyzer (CCA)—over CaCO3 concentrations from 0.3% to 50%. Controlled sand samples with known carbonate contents were tested to assess each method’s accuracy, precision, and reproducibility. Although LoI proves the most practical due to its simplicity and throughput, all methods face marked difficulties at low concentrations. Root Mean Square Error (RMSE) analysis shows that small discrepancies at low CaCO3 levels can produce disproportionately large relative errors, obscuring actual measurement uncertainties. Factors such as sample representativeness, operator handling, and instrument resolution further amplify inconsistencies, emphasizing the need for more rigorous protocols. Crucially, none of the evaluated methods consistently captures very low CaCO3 concentrations, posing significant challenges for soil carbon capture initiatives, regulatory compliance, and soil management practices. These findings highlight the urgent need to refine existing procedures or use alternative approaches to more accurately quantify CaCO3 content at low levels, thereby enhancing confidence in research outcomes and applied engineering solutions.

Resumo em Inglês:

Abstract The paper presents the finite element modeling of a test embankment built at one of the construction sites of the 2016 Olympic Games in Rio de Janeiro, Brazil. The embankment was raised over 6 weeks to a height of 6.7 m, and was monitored during construction and in the following month. The experiment had to end after a month of measurements due to the need to develop the test area. Instrumentation consisted of electric piezometers, settlement plates and inclinometers. The subsoil featured a pack of sedimentary soils, including soft clays. Firstly, field and laboratory tests were evaluated for numerical modelling parameters, and a sensitivity study of the various parameters was carried out. Program PLAXIS was used with the most suitable soil models for the different soil layers. The time-dependent behaviour of the clayey layers followed Terzaghi’s consolidation theory for pore pressure dissipation coupled with a Buisman (1936)-type solution for viscous behaviour. The final analysis used parameters adjusted by back-analysis of measurements in the monitoring period (2.5 months) in a 3D model. This analysis was extended to 50 years, aiming to predict the long-term behaviour of the embankment. Results of the 50-year analysis indicated that after 20 years the excess pore pressures would have practically dissipated, but that the long-term settlement would be 2.5 times greater than that at the end of construction. Furthermore, the ground horizontal displacement would be about 4 times greater than that measured at the end of construction.

Resumo em Inglês:

Abstract Dynamic compaction and dynamic replacement represent techniques for improving soils with low bearing capacity or with a high degree of deformability. Those techniques are performed through the percussive process of large hammers or plates with metric tons of weight released from large heights on the soil. Currently, there are many companies worldwide using different types of equipment with distinct specifications regarding height and lifting capacity, potency and release form (cables or free fall). For experimental purposes, this article proposes the development of a trigger system composed of a release lever and a body, which is formed by the fixed body, the moving body and a lock, inspired by Giese (2019). The proposed trigger body was developed with SAE 4140 steel and SAE 1020 steel in connection with the low cost release body. After the tests, the objective of the study was achieved in the laboratory tests (80 kN) and field tests (55 kN of tamper weight plus friction and adherence between soil/tamper).

Resumo em Inglês:

Abstract Rock is a commonly utilized material in the construction of rockfill dams, protective ripraps for dam slopes, and stabilization of natural slopes. These materials demonstrate favorable performance under both static and dynamic loading conditions and are frequently more cost-effective compared to alternative stability solutions and construction methods for dams. The large dimensions and density of rock materials make it challenging to conduct representative mechanical tests and develop practical mathematical models that accurately describe their mechanical behavior at a real scale. This study proposes a hyperbolic prediction model for the shear mechanical behavior of earthfills, based on the outcomes of large-scale shear tests conducted on riprap samples with varying average dimensions (D50). Analysis of the data revealed that the hyperbolic model exhibited good agreement with the graphs depicting shear box inclination mobilized friction angle θ (°) versus shear displacement 𝛿 (mm), in relation to the riprap diameter D50. Moreover, the parameters α (Stiffness index) and β (Asymptotic index), along with the hyperbolic model, displayed a promising interrelationship of high quality.

Resumo em Inglês:

Abstract Monitoring is an element of landslide early warning systems. Fukuzono’s method, based on displacement and velocity monitoring, is one of the most popular methods for slope time of failure (TOF) prediction. This critical literature review aimed to systematically analyze the state-of-the-art accelerometers used for slope monitoring and TOF prediction. Two peer-review online article platforms were used to build a database of 50 articles. Time history analysis showed that from 2014 onwards the interest in accelerometers has increased and using them as tilt sensors has become a well-accepted approach for geotechnical monitoring. However, special attention must be paid to calibration and noise reducing of low-cost sensors. Also, the installation setup may influence measurements. Alert thresholds and TOF prediction methods based on tilting rates for sensors buried at shallow depths have been proposed and few real validated cases are reported. These predictions attempt to find a simple relation between TOF and slope tilting rate, similar as Fukuzono’s method. Relations between tilting rate and surface displacement is an aspect that remains unclear. In order to clarify those aspects, more real slope cases should be reported. A more established use of accelerometers is as a chain of sensors buried in a borehole, similar to a permanent inclinometer. In these cases, accelerometer data are interpreted as displacement, in a more traditional way.

Resumo em Inglês:

Abstract The Brazilian Road transport mode accounts for approximately 65% of the freight transport matrix, playing a significant role in the productivity of all economic sectors. Therefore, the maintenance of road infrastructure impacts resource optimization, safety, and user comfort. This article reviews the use of Reclaimed Asphalt Pavement (RAP) as an aggregate in the base and sub-base layers of pavement, employing cementitious materials as a binder/stabilizer. The ProKnow-C method was used to identify articles for discussions in the systematic literature review (SLR). The results show that the resilient modulus (MR) increases with the higher RAP content in the mixtures, improving the load-bearing capacity of granular layers, while the California Bearing Ratio (CBR) decreases as the RAP content increases. However, treated RAP exhibits high-strength properties. As the RAP content increases, unconfined compressive strength decreases. Future investigations are needed to address durability, life cycle analysis (LCA), and economic feasibility.