Abstract The study and understanding of the concepts related to critical state soil mechanics is relatively recent in Brazil, especially among practicing geotechnical engineers in the mining industry, where simpler solutions were traditionally adopted. This raises the necessity to develop studies capable of promoting discussions about the benefits of the approaches from the critical state theory. In this context, this research aims to evaluate the behavior of an iron ore tailings from the Quadrilátero Ferrífero through critical state computational models, considering the Modified Cam-Clay and NorSand model. The numerical results from the use of the models simulated the ductile/brittle behavior of the material in drained shear and it was observed that for loose samples both models produced similar results. The simulations in undrained shear, on the other hand, highlighted the differences between the models, with the NorSand showing a strength loss in undrained shear (strain-softening) whereas the Modified Cam-Clay Model exhibited a ductile behavior. In general, the NorSand model was the one that presented the best numerical response in relation to the experimental behavior, which may be linked to the use of the largest number of parameters, to the concept that particulate materials exist in a set of states and the silty characteristic of the material. Additionally, it was observed the difficulty to simulate the dense behavior of materials with the model, which may be associated with the formation of ‘shear bands’ during the experimental test and the complexity of modeling the occurrence of this phenomenon in virtual tests using the NorSand model. Brazil industry adopted theory context CamClay Cam Clay ductilebrittle brittle hand strainsoftening strain softening (strain-softening general parameters Additionally bands

Abstract Αn online questionnaire was developed to find out (i) whether geotechnical engineering instructors have available a variety of satisfactory educational material and (ii) the types of educational material they desire. The title of the questionnaire was phrased as “What Geotechnical Engineering Educational Material can we dream of?”, in order to convey that the main purpose of the survey project reported herein is to learn about these desired educational materials. In doing so, the survey also aims to assemble information on related issues, such as: existing educational materials, where do instructors search for them and how satisfied they are with available material. The questionnaire has 12 close-ended (four yes/no and eight multiple choice) and four open-ended questions. Of the 94 completed questionnaires received, 63 were deemed to be conscientious attempts to answer its questions and were analyzed in detail. The most revealing findings from the close-ended questions include the following. The majority of the instructors (52%) are not adequately satisfied with the material they use. Likewise, whereas a significant percentage have searched for additional material, a little less than half of them (45%) are not satisfied with material found. Respondents need materials for their lectures, materials to engage students outside lecture time and, to a lesser extent, materials to assess students. In terms of topics of interest, case studies and laboratory-related educational materials are the most popular. The online supplement of the paper includes broad-stroke and fine-stroke descriptions of desirable educational materials that provide directions for developing them. i (i ii (ii desire What of, , of?” so issues 1 closeended close ended yesno yes no choice openended open 9 received 6 detail following 52% 52 (52% use Likewise 45% 45 (45% found lectures extent interest laboratoryrelated laboratory popular broadstroke broad stroke finestroke fine of? 5 (52 4 (45 (5 (4 (

Abstract The use of problem-based and project-based learning is beneficial. The teaching-learning process requires the development of a critical, objective, and rational mind. This paper analyzes methodological experiments from the teaching-learning process carried out in the geotechnical area of the civil engineering program at three universities in the state of Pernambuco, Brazil, for more than 40 years. Three integrated experiments are presented. In the first experiment, undergraduate students in geotechnical engineering courses interacted with companies operating in the area, conducting laboratory and field tests and geotechnical instrumentation. The second experiment integrated students and teachers from different areas of the civil engineering program around a multidisciplinary project, while the third brought together undergraduate and graduate (master and doctoral) student research activities into a single project that extends from the development and construction of geotechnical equipment and applications of new soil improvement techniques to land use planning and occupation. This study shows the use of teaching-learning experiences carried out in geotechnical engineering, contributing to the development of technical skills and professional competencies of civil engineers. It contributed to the advancement of knowledge in the development of new equipment, soil improvement, testing techniques and in the use, planning and occupation of soils. The interaction between the university, society and government institutions in problem solving also contributed. problembased based projectbased beneficial teachinglearning teaching critical objective mind Pernambuco Brazil 4 years presented instrumentation master doctoral engineers soils university

Abstract Small-scale physical models of geotechnical problems are thought-provoking didactic tools that motivate students by arousing their curiosity and facilitating the understanding of physical phenomena and theoretical concepts. This work presents the development of an educational video about slope stability failures and its contributing factors. It shows several small-scale models built in a glass wall tank measuring 150 x 50 x 10 cm. Layers of fine gravel were placed on a sloping surface of polystyrene to represent a slope with a layer of residual soil on rock. Toy houses and cars were used to represent anthropogenic agents, and water with dye represents the groundwater flow. Each model depicts a different scenario of shallow slope failure. The objective of the video is to show that most slope failures in urban areas result from natural and anthropogenic factors. Several influence factors are shown: porewater level rise, excavation, surcharge application, and solid urban waste deposition. The 6-minute video has had more than 130,000 views on YouTube. Thanks to its simple and concise language, the video is shown in basic education and science museum, as well as in graduate and undergraduate courses. A questionnaire survey was carried out with undergraduate students to assess how helpful the video was for the learning process. This article explains the construction of the model, the video script, and the strategies for its use, as well as its reception. It was found that the video promoted motivational and learning benefits of providing context, establishing relevance, and teaching inductively. Smallscale Small scale thoughtprovoking thought provoking concepts smallscale small 15 5 1 cm rock agents flow failure rise excavation application deposition 6minute minute 6 130000 130 000 130,00 YouTube language museum courses process script use reception context relevance inductively 13000 13 00 130,0 1300 0 130,

Abstract To solve the problem that the mechanical behavior of undisturbed loess in seasonally frozen soil area is affected by freeze-thaw action, triaxial shear tests of undisturbed loess under freeze-thaw condition were carried out. The results show that the mechanical properties of undisturbed loess are greatly affected by factors including freeze-thaw process, water content, natural density and confining pressure. Freeze-thaw action has a certain impact on the failure surface shape and stress-strain curve. Before and after freeze-thaw, the shape of the shear failure surface is complex, including single oblique failure surface, double oblique failure surface, vertical failure surface, X-shaped failure surface, bulging failure, etc. And under the conditions of low water content, low confining pressure and high dry density, the stress-strain curve tends to be softened. Conversely, the curve tends to harden. Freeze-thaw action can make the stress-strain curve transition from softening to hardening. In addition, the freeze-thaw action significantly weakens the failure strength, shear strength, cohesion, initial tangent modulus and failure ratio of undisturbed soil, but does not change the internal friction angle obviously. Also, the heterogeneity of natural soil is also an important factor affecting the mechanical parameters, failure surface shape and stress-strain curve of undisturbed loess. freezethaw freeze thaw out process content Freezethaw Freeze stressstrain stress strain freezethaw, thaw, complex Xshaped X shaped etc softened Conversely harden hardening addition strength cohesion obviously Also parameters

Abstract As dams play a very important role in the optimum use of water resources, it is very important to keep them stable and the water stored in the reservoir. It is particularly important to investigate how water moves through rocks and the permeability and quality of the rock mass in structures like dams. Therefore, one of the issues considered in dam stability is monitoring the quantity of leaks. In this research, the engineering geological and geotechnical parameters of the rock mass for the construction of the Kurit Dam located in the city of Tabas in eastern Iran were evaluated. Initially, following the determination of geotechnical parameters, the engineering classification of the rock mass of the study area was carried out. In addition, in order to study and trace the water evacuation routes of the dam construction, two parameters of the RQD and Lugeon were studied and modelled. Analyses have been conducted to examine the permeability and rock quality index in three parts of the left and right abutment, the dam's axis and reservoir with geostatistics and kriging methods. Three-dimensional model of the construction of the Kurit dam was presented and the results were analyzed. Based on the results, the quality of the rock mass in the right and left abutments is arguably better than the dam axis and reservoir. Additionally, as the depth increases, the permeability decreases and the permeability is higher at shallow depths. The highest level of permeability is located at the surface and near the B H 4 borehole. resources Therefore leaks research evaluated Initially out addition modelled abutment s methods Threedimensional Three dimensional analyzed Additionally increases depths borehole

Abstract Seismic bearing capacity of strip footings is a challenging task for geotechnical engineers due to its stochastic framework instigated by the natural uncertainties incorporated into geotechnical properties and earthquake parameters. Consequently, the introduction of the random field theory into reliability analysis may provide power tools to succor designers check how reliable their designs. This paper aims to assess the seismic bearing capacity of shallow strip footings resting on soils with randomly varying parameters. Bearing capacity formulas for purely cohesive and cohesive-frictional soils are considered. The influence of the type of the autocorrelation functions (ACFs), the scale of fluctuations (SOFs) and the coefficient of variation (COV) of the random parameters are investigated. Statistical moments, probability density function (PDF) and failure probability (Pf) of the seismic bearing capacity are computed. It is shown that the Single Exponential (SNE) ACF is the most appropriate function to characterize the spatial variability of the soil properties since it provides conservative results. On other hand, the results indicate that the increase in the coefficients of variation (COV) of the cohesion or the friction angle increases the variability of the seismic bearing capacity while this variability remains unaffected when the COV of the seismic coefficient increases. The results also highlight that the effect of the vertical SOF on the PDF and the failure probability is much more significant than that of the horizontal SOF. In addition, the mean seismic bearing capacity fluctuates slightly as the horizontal or vertical SOF increases so that the increment of variation is between 0.4% and 2% for the both two soil types. Consequently designs cohesivefrictional frictional considered ACFs, ACFs , (ACFs) SOFs (SOFs (COV investigated moments (PDF Pf (Pf computed SNE (SNE hand addition 04 0 4 0.4 2 types (ACFs 0.

Abstract The aim of the current study is to investigate the influence of consecutive wetting and drying cycles on the free swelling and swelling pressure properties of a potentially expansive soil. The investigated sample consisting of high-plasticity inorganic clay with high consistency-limit values and extremely high swelling potential. The adopted methodology comprised free swelling and swelling pressure tests – based on the post-swelling loading method, under 0.5 kPa overload. Both tests were conducted in a cyclic manner by implementing eight wetting and drying cycles. Results have shown that the wetting and drying cycles acted as agents influencing the swelling pressure and free swelling properties of the expansive soil. It was found that the expansive soil sample, when moistened and then dried to its initial moisture content, time and again, showed higher values of swelling pressure and free swelling at the first moistening cycle. It was also observed that the expansive soil sample decreases its expansive behavior as the number of wetting and drying cycles increases. highplasticity plasticity consistencylimit consistency limit potential postswelling post method 05 0 5 0. overload content again cycle increases

Abstract Granular materials (assemblies of contacting grains with inter-granular porosity) form a vast family of materials important in both natural and industrial contexts. Under mechanical loads such systems show complex behaviours relating to the inter- and intra-granular stresses, strains and force transmission as well as the individual grain kinematics and interactions leading to multi-scale, heterogeneous behaviour. To understand such systems requires detailed understanding of these different structures and processes at the pertinent scales. This paper provides a brief overview of some new opportunities for enhanced experimental description of structures and mechanisms relating to the deformation of granular materials exploiting the penetrating power of x-rays for both imaging, giving access to granular structures and their evolution, and diffraction-based measurements, giving access to intra-granular grain structure and changes as well as inter- and intra-granular force transmission. assemblies intergranular inter porosity contexts intragranular intra stresses multiscale, multiscale multi scale, scale multi-scale behaviour scales xrays x rays imaging evolution diffractionbased diffraction based measurements

Abstract Although fully penetrating stone columns have widely been studied in the literature, the number of published studies on floating stone columns – which also have been efficiently used to improve vertically lengthy soft-clay deposits – is very limited. Basal reinforcement with geosynthetic is another technique that increases overall stability of embankments on soft soils and can be combined with stone columns. In the paper, mechanical-hydraulic coupled finite element analyses are performed to study a floating stone column-supported embankment on a thick soft soil deposit. A parametric analysis is conducted so that the influence of two governing factors is evaluated: length of stone columns; basal reinforcement with geosynthetic. An overall stability analysis method, which uses the results of finite element analyses, is also applied. Results of several key variables are analysed: overall safety factor, settlements, horizontal displacements, vertical stress at the embankment base, stress concentration ratio, excess pore pressures and geosynthetic tensile force. literature softclay clay limited paper mechanicalhydraulic mechanical hydraulic columnsupported column supported deposit evaluated method applied analysed factor settlements displacements base ratio force

Abstract Examples of upscaling phenomena with experimental techniques are presented and discussed within the framework of compacted soils for hydraulic and environmental earthworks and engineered barriers for the energy sector. A series of laboratory experiments at different scales are presented and interpreted to focus on the need for experimental upscaling in compacted soils since distinctive behavioural features can only be detected at specific length scales. Permeability results on fine-grained soils and artificially prepared sand/bentonite mixture at different scales will be discussed with microstructural tests regarding ‘dry’ or ‘wet side’ compaction, element and mock-up tests on compacted soils in the laboratory, and field tests on a compacted trial embankment and demonstration test to explore anisotropic and heterogeneous features. The presented examples will help to motivate new experimental research subjects and promote experimental protocols at different scales ranging from mm-scale (micro), cm-scale element tests, dm-scale mock-ups and m-scale (trial/demonstration tests) to help understand and approach some fundamental questions observed at the application scale of compacted soils. sector finegrained fine grained sandbentonite sand bentonite ‘dry dry wet side compaction mockup mock up mmscale mm micro, micro , (micro) cmscale cm dmscale dm mockups ups mscale m trial/demonstration trialdemonstration (micro

Abstract The West-East Integration Railway (Ferrovia de Integração Oeste-Leste -FIOL) is an infrastructure project designed to integrate and promote the socio-economic development of the Northeast region of Brazil. In countries with heavy-haul railway operations, there has been increased demand for ballast materials that can withstand cyclic loading of up to 40 tons per axle. In this context, in order to achieve greatest operational efficiency, it is essential to evaluate the characteristics of the limestone aggregate to be used in the ballast layer, as well as the level of cyclic stress that the ballast can withstand. The laboratory investigation consisted of characterization tests, single particle crushing tests, monotonic triaxial tests, and evaluation of the morphological properties of the particles using the Aggregate Image Measurement System. This paper introduces the equipment, describes the experimental procedures, outlines the specimen preparation, and presents the experimental results. The purpose of the study is to estimate the long-term behavior of ballast based on monotonic triaxial tests, the shakedown phenomenon, and the cyclic stress ratio. The results suggest that the cyclic stresses commonly observed in heavy-haul railways may exceed the cyclic stress ratio compatible with the shakedown regime, resulting in a progressive plastic creep regime. Furthermore, the quantity of non-cubic particles exceeds the limits set forth in international ballast standards necessitating a rigorous assessment of the particle shape prior to use in the field. WestEast West East Ferrovia OesteLeste Oeste Leste FIOL -FIOL socioeconomic socio economic Brazil heavyhaul heavy haul operations 4 axle context efficiency layer tests System equipment procedures preparation longterm long term phenomenon regime Furthermore noncubic non cubic field

Abstract Thin spray-on liners (TSLs) are a promising rock support method due to their ease of application and versatility. However, their effectiveness relies on experience and lacks a complete scientific understanding. To bridge some of the knowledge gaps existing in support mechanisms, this study investigated the effect of different parameters on the shear-bond strength of TSLs as a surface support in underground excavations. The parameters included liner thickness, curing period, material type and surface cleanliness. A polymer based cementitious TSL was utilized while the material type included quartz and sandstone rocks and 30 MPa concrete. Liner thicknesses included 16.2 mm, 20.2 mm, 24.2 mm, 28.2 mm, and 32.2 mm while curing periods were 7 days, 14 days, and 28 days. It was observed that the TSL shear-bond strength varied with different materials. Quartz with the lowest porosity had the lowermost shear-bond strength at all liner thicknesses and curing periods. The shear-bond strength improved with liner thickness up to 24.2 mm and then decreased up to 32.2 mm due to the optimum thickness effect. It also increased with curing period. Oil reduced the shear-bond strength for all the material types at all liner thicknesses and curing periods. sprayon spray (TSLs versatility However understanding mechanisms shearbond shear bond excavations period cleanliness 3 concrete 162 16 2 16. 202 20 20. 242 24 24. 282 28. 322 32 32. days 1 materials

Abstract In recent years, two tragic accidents in Brazilian tailings dams resulted in a lack of trust in the performance of these structures. This paper aims at proposing a new procedure for estimating the liquefaction risk of existing tailings dams, with the use of well-known probabilistic methods as a valuable tool in the decision-making process for triggering an Emergency Plan. The combination of a rigorous limit equilibrium stability method (Spencer, 1967) and the FOSM probabilistic procedure (Christian et al., 1992) has proved to adequately predict the imminent liquefaction risk of both Fundão and Feijão tailings dams, which recently collapsed in Mariana (2015) and in Brumadinho (2019), both in Minas Gerais State, Brazil. Considering the triggering mechanisms known to have occurred, the estimated probabilities of liquefaction failure at the time of the accidents were 36% for Fundão Dam, and 47% for Feijão Dam. The results show that the risk associated to the collapse of both structures was well above the acceptable level suggested by current standards. years wellknown decisionmaking decision making Plan Spencer, Spencer (Spencer 1967 Christian al al. 1992 2015 (2015 2019, 2019 , (2019) State Brazil occurred 36 Dam 47 standards 196 199 201 (201 (2019 3 4 19 20 (20 1 2 (2 (