Obras y Proyectos is a publication whose mission is to spread, promote and encourage research, contributing to the knowledge interchange among professionals of the Civil Engineering community. To this end original and scientific works are considered as well as technical notes mainly orientated to show and discuss relevant works and projects. Technical works showing innovations and applications used mainly by enterprises and consulting firms involved in Civil Engineering are presented too. In this form, the classical branches of Civil Engineering, namely Structures, Hydraulics, Geotechnics, Transport and Construction are developed. In addition, other areas related to and applied to Civil Engineering such as Energy, Environment, Geology, Mining, Computing and Technology, are considered. As a result, Obras y Proyectos seeks the participation of a wide group which covers from the academia, state institutions, and the entrepreneurial world.
Universidad Católica de la Santísma Concepción
Optimization of reinforced concrete plane frames using a hybridization of genetic algorithms and the Nelder-Mead algorithm
This paper presents an algorithm using CSi Application Programming Interface (CSi API), which allows the automation of the structural optimization process for plane frames, linking powerful computational tools such as SAP2000v16 and Matlab. In addition, aspects usually ignored in modelling and structural analysis for structural optimization are included, such as the influence of cracking of concrete elements in their stiffness and the inclusion of a second order analysis. On the other hand, due to the complexity of the objective function, it was necessary to use metaheuristic optimization methods: a hybridization between genetic algorithms and the Nelder-Mead algorithm, instead of the classical methods used in previous studies, obtaining satisfactory results. The results are expressed in the form of design recommendations and they are compared with those obtained in previous investigations.
Copyright (c) 2019 Universidad Católica de la Santísima Concepción https://creativecommons.org/licenses/by-nc/4.0
Preliminary analysis of the seismic response of bridges during the Chilean 27 February 2010 earthquake
A preliminary analysis of the seismic behaviour of bridges during the February 27th Chilean earthquake is presented in this paper. The traditional characteristics of reinforced concrete Chilean bridges have been changing in the last two decades, especially in concessions roads. Therefore, three different superstructure configurations are indentified. In newer bridges designs, the diaphragm has been eliminated and in some bridges, the reinforced concrete shear key, or stoppers, has been replaced by weaker steel shear keys. Because of the earthquake, 10 relevant public bridges collapsed and 91 concession bridges, which include 52 pedestrian bridges, suffered damage or collapse. The observed damage in selected bridges around Santiago and Concepción are described here. The seismic behaviour of bridges was affected not only by the structural configuration but also by the foundation soil. Findings from this analysis reveal that the strength and stiffness provided by the steel shear keys was inadequate, and that the absence of diaphragms was found to be detrimental to the integrity of the superstructure. It is also concluded that skewed bridges are more susceptible to unseating of the superstructure and that the foundation soil played an important role in the seismic behaviour of some bridges, especially for soft and saturated soils responding in an undrained condition.
Copyright (c) 2010 Universidad Católica de la Santísima Concepción https://creativecommons.org/licenses/by-nc/4.0
Lateral and uplift resistance of Geopier-supported footings
This paper discusses the behavior of Geopier-supported shallow foundation systems when subjected to lateral and uplift (tensile) loads. Lateral and tensile loads are often applied to foundation systems when the supported structures are subject to wind or seismic events and also to lateral earth pressures. Geopier - supported shallow foundations provide resistance to lateral loads using mechanisms identical to those applicable to conventional shallow footings. These mechanisms include passive earth pressure adjacent to the footings and sliding resistance along the base of the footings. However, because of the high stress concentration to the Geopier elements and the high friction angle of the Geopier aggregate, greater resistance is achieved in comparison to a footing supported by soil not reinforced by Geopier elements. Uplift anchors are incorporated into Geopier elements to resist tensile loads. The anchors consist of a steel plate installed at the bottom of the piers and threaded bars connected to and extending from the embedded plate to the overlying footing. This paper describes methods used to design Geopier-supported footings to resist lateral and uplift load demands. Results of lateral and uplift loading tests using full-scale footing are also presented.
full scale lateral and uplift load tests
Stochastic modeling of settlements produced by cyclic loads
In shallow foundations the relation between differential settlements due to cyclic and static loading has been a source of several finite elements analyses. These analyses show that cyclic settlements are three times greater than static settlements. Based on a model of accumulation of deformations it is shown that a structure becomes more sensitive to settlements generated by cyclic loading than those generated by static loading. Moreover, this proportion can be higher than three and depends on the amplitude of the applied cyclic loading. A random generation of void ratios is presented for a subsoil on which two footings rest. These footings are loaded with hundred thousands cyclic loads. It is concluded that cyclic settlements depends strongly on the average stress applied. On the contrary, the variation of the average stress amplitude had practically little influence on the cyclic settlements of both footings.
Effect of earthquake duration on the inelastic response of reinforced concrete structures
This study investigates the relationship between damage and earthquake duration. For this purpose, a computational program was use to analyse a 4-story RC frame subjected to 40 strong-motion records of different durations and intensities. The inelastic response analysis was performed based on four parameters of damage: the maximum displacement on the top floor, the maximum relative displacement between floors, the dissipated hysteresis energy and the accumulated ductility. The duration proposed by Somerville et al.(1997), defined as the interval between the 5% and the 75% of the Arias Intensity, was used. The seismic records were scaled so that all have the same level of spectral acceleration for the fundamental period of the structure under study. The spectral acceleration was chosen by the design spectrum obtained from the Chilean Standard NCh433 Of.96. It is concluded that for damage parameters based on displacements there is not effect of duration. However, accumulative damage parameters depend strongly on the earthquake duration.
Copyright (c) 2009 Universidad Católica de la Santísima Concepción https://creativecommons.org/licenses/by-nc/4.0
Reliability applied to the geotechnical design of a retaining wall
The daily practice of designing civil engineering projects focuses its efforts on quantifying the factor of safety to ascertain whether a structure is safe or not. However, the factor of safety in itself does not reflect the probability offailure of the designed structure. This practice is deeply rooted within the geotechnical engineering field. This article shows three methods; first order second moment, point estimation, and Monte Carlo simulations. These three methods are used to estimate the probability of failure of a geotechnical structure, namely a gravity retaining wall adjacent to a slope. The probabilistic analysis allows to determine the optimal base width of the wall as a function of the construction costs. A geometrical deduction of the bearing capacity factors Nc and Nq for the slope condition is presented. Finally, results obtained from the three analysed methods are compared and some recommendations for the convenience of reliability analysis are discussed.
Copyright (c) 2011 Universidad Católica de la Santísima Concepción https://creativecommons.org/licenses/by-nc/4.0
Study of slope stability in weathered rock of the Quiriquina formation
In this article the slope stability of weathered sedimentary rocks present in the city of Concepción is studied. A geological description of the sedimentary rocks, which form part of the Quiriquina Formation, is presented using available geological maps and bibliographic information. Laboratory results from direct shear tests are shown. This allows the determination of strength parameter values of the sandstones of the Quiriquina Formation. Finally, slope stability analyses are performed by means of limit equilibrium methods. The case scenarios of plane and wedge failure are analysed using the parameter values obtained in the laboratory tests. It is concluded that, in addition to the importance of the adequate determination of the cohesion and friction angle values in residual and saturated conditions, it is fundamental the previous determination of possible failure surfaces.
Application of the AERMOD software for modeling PM10 dispersion emitted by wood-burning heating equipments in Constitución city
In this paper emission rates and loads of PM10 are estimated using the software AERMOD for the winter period of 2009 and 25 sources composed of firewood heating distributed in an inhabited urban area of Constitucion city. Where emission rates and loads do not exceed in any point the limit of 150 μg/ m3 PM10 established by the Chilean regulation DS 59/98, as well as those rates and loads which do exceed the regulations in 1, 2 and 3 or more points, were determined based on 24-hours concentrations. To not exceed the regulation, the average emission rate of a heating equipment must be lesser than 7.5 g/h of PM10. This regulation is exceeded in 1 and 2 points, when the average emission rate of firewood heating is between 10 and 22.5 and between 25 and 40 g/h of PM10, respectively. Values higher than 45 g/h generate new points over 150 μg/m3. Concerning the load of PM10 does not exceed the regulation, PM10 load values must be lesser than 83 kg/d, and to exceed the regulation in 1 and 2 points, they must be between 83 kg/d and 249 kg/d and between 249 kg/d and 443 kg/d, respectively. The first two points in excess of 150 μg/m3 are in the geographical coordinates 736700 mE - 6085700 mS and 734900 mE -6087600 (UTM WGS 84). It is suggested to carried out air quality monitoring to calibrate and validate the model used in the study area.
Construction system of a nineteenth-century copper smelting in Atacama, Chile
Mining has occupied an important place in the Chilean economy since the 19th century and up to the present day. However, the oscillating cycles of economic booms and crises in the mining sector have left traces of industrial buildings from mining and copper metallurgy with unique characteristics. The objective of this article is to describe the materiality and origin of the construction system used in the ruins of a former nineteenth-century copper foundry located in the port of Caldera, in northern Chile. The ruins of the buildings show that the foundations and walls built with blocks of copper slag melted and molded in situ, was a construction technique brought by the English builders and metallurgists who arrived in the mining centers of Atacama, replicating the techniques used in English works, an activity that allowed the valorization of metallurgical waste.
Copyright (c) 2023 https://creativecommons.org/licenses/by-nc/4.0
Seismic coefficients adopted in the design of Chilean tailings dams
The design of tailings dams considers a pseudostatic stability analysis using the limit equilibrium method, where inertial effects are captured by forces proportional to the weight of the sliding mass and seismic coefficients. This study compiles and analyzes a database of horizontal seismic coefficients (kh) adopted in the design of 125 tailings dams built in Chile from 1983 to 2022. The database also considers geometric, seismic, and geotechnical information that influences the factors of safety obtained in slope stability analyses. This study reviews 11 methods adopted for the estimation of kh and recommends a range of values for design earthquakes.
Copyright (c) 2025 Universidad Católica de la Santísima Concepción https://creativecommons.org/licenses/by-nc/4.0
CO2 equivalent emission in the construction of adobe and brick single family homes
The present study focuses on knowing the environmental impact in terms of CO2 equivalent (CO2e) in the construction of adobe and brick single-family homes in the district of Aucallama, province of Huaral, Lima. The methodology followed was observational - quasiexperimental. Field studies were carried out, taking necessary data for the analysis of the unit items, these involve all the resources that are needed in the activities of the housing construction process. In order to have accurate and reliable results, calculations of meters and Carbon Footprint have been made with homes designed under the recommendations of the Peruvian Standards. The Carbon Footprint CF calculations were made with the help of Emission Factors from international inventories and national research. The calculations are made for the three processes: production of inputs, transportation, and execution. In the construction of the adobe house, 14 tons of CO2e have been obtained, while for the brick house, 50 tons of CO2e. The low built-in CF of the adobe house is due to the activities and inputs for the construction of those houses, which are handmade and large equipment is not required for each process, which makes it a sustainable house.
Validation by Montecarlo simulation of the efficiency of an optimally tuned liquid column damper for excitations with high frequency content
In this research the efficiency of the Tuned Liquid Column Damper (TLCD) calculated through stochastic vibration theory is analysed. Three optimization functionalities or criteria are considered. The model consists of a one degree of freedom main system, with nonlinear behaviour, controlled by non-linear TLCD. The stochastic analysis assumes a steady-state and performs an equivalent statistical linearization for nonlinear behaviour, with which theoretical displacement and hysteretic energy reductions are obtained. Then, these theoretical reductions are compared with the reductions obtained with a Monte Carlo Simulation (MCS) of 200, 450, 800, 1250, 1850, 2600 simulations. For the simulation, nonlinear equations are proposed, which are directly integrated without linearization. The simulations are performed with artificial earthquakes of high-frequency content, compatible with the Chilean standard NCh2745 (2013). The results obtained through the MCS are sensitive to the number of simulations considered. However, a convergence occurs for two criteria. Errors are less than 10%, which is considered acceptable. The reductions obtained for hysteretic energy from a theoretical analysis overestimate the efficiency of TLCD, for a criterion with a period of 2.0 s, and for all criteria with a period of 2.5 s.
Use of walnut shell in the production of particleboards
The global increase in walnut production has resulted in significant waste generation, typically ending up in landfills and causing adverse environmental impacts. The waste occupies large land areas and contaminates the soil through decomposition processes. Chile, known for being a major producer of walnuts, particularly the Chandler variety, possesses a valuable waste resource in the form of walnut shells. These shells can be utilized as raw material in the manufacturing of innovative construction materials. This article focuses on determining the absorption, swelling, density, flexural strength, and compressive strength properties of prismatic samples made from Chandler walnut shells. These samples were bonded using two types of PVAc adhesives: one commonly used for wood joints, and another specifically designed for moisture resistance. The results demonstrate the viability of this particleboard, showcasing its stability and ability to withstand moderate stress.
Optimization project of plasterboard and metalcon profiles for a building in Concepción
A study was prepared, which consists of the economic evaluation of two important materials in the construction of the interior partitions of the 3rd floor in a 21-floor building located in the city of Concepción. These materials are plasterboard and metalcon profiles. Within this study, the acquisition cost of these two materials was evaluated, as well as the cost associated with labor and machinery involved in the transportation process on site. In addition, the waste generated by both materials was accounted for, to quantify the costs related to waste management. Finally, a proposal is presented to achieve the optimization of these materials within the work, with the aim of achieving a better use of both. This entails great benefits for the company, since it is possible to reduce the number of materials that are currently used, and the amount of waste generated within the work.
Computational modeling of earthquake-induced massive landslides using by the Material Point Method
Landslides represent one of the most frequent and destructive natural hazards in recent years. In highly seismic countries, the occurrence of large earthquakes is a significant triggering factor in the generation of these landslides. Therefore, it is of interest to various disciplines within civil engineering to study these phenomena through empirical analysis, analytical methods, and numerical modelling, aiming to provide a more accurate representation of these complex phenomena. For this purpose, a computational modelling approach is developed to describe the dynamics of a landslide or rockslide induced by seismic loading, using the Material Point Method (MPM). Presently, the utilization of MPM holds considerable significance because it is a numerical method engineered to simulate large deformations. This stands in contrast to conventional methods like the Finite Element Method (FEM), which struggles to precisely deal with this type of problems due to the generation of errors related to mesh distortion. In this study, it is performed a modelling process involving a real and documented scenario—a massive landslide occurrence in the vicinity of Daguangbao, China, triggered by the 2008 Wenchuan Earthquake. The obtained results successfully capture the landslide dynamics in terms of velocities, deformations, and travel distances in accordance with existing reports and other research endeavours. The maximum attained velocities of the landslide are approximately 100 km/h, affirming the catastrophic nature of this event.
Copyright (c) 2024 https://creativecommons.org/licenses/by-nc/4.0
Comparative evaluation using performance-based design of a wall-structured building
Performance-based design has been increasingly used in practice due to computational improvements, the sophistication and dissemination of nonlinear analysis methods, and the development of commercial programs that facilitate its use. We can evaluate the nonlinear effect of seismic events of great magnitude on the structural behaviour of a building, verify preliminary designs based on force-based methods, validate standard design regulations, determinate deformations, and calculate accelerations that can be translated into parameters of structural damage and economic losses, among other functions. Guiding documents have presented methodologies to establish requirements, evaluation criteria and analysis methods, each with different objectives. In this article, one of the methods is applied, known as the alternative procedure of ACHISINA, to a structure with shear walls designed according to current Chilean regulations. The modelling of the earthquake-resistant structure of the building, the preparation of seismic records, and the aspects that limit the rigorous application of the method are addressed in a non-elastic analysis framework. Results obtained in the respective analyses to evaluate the structural performance are compared with the corresponding performance criteria outlined in the ACHISINA procedure.
Static nonlinear analysis with incremental thrust for the evaluation of the performance level of a typical residential building with reinforced concrete walls
The static nonlinear analysis has been developed for a reinforced concrete building to study the flexo-compression behaviour of the shear walls and estimate the damage beginning when the structures reach the limit state defined in ACHISINA performance-based seismic design document. A refined fiber model has been incorporated throughout the entire height of the building considering the confined behaviour of the concrete from the detailing of the structural elements. A stiff diaphragm has been considered in the structure to model the behaviour of the reinforced concrete slab. The N2 method has been implemented considering a seismic demand in acceleration displacement format based on the displacement spectrum establish in the DS61, enacted after the Mw = 8.8 Maule Earthquake in 2010. Regarding this result, it is concluded that the building obtains an immediate occupancy performance level for drifts close to 5‰ in the symmetrical Y direction, a greater amount of structural damage, proportional to a life safety performance level, is observed.
A coastal infrastructure design methodology considering climate change
Given the gaps detected in the national engineering practice, a methodology is proposed to integrate the effects of climate change in the design of coastal and port infrastructure. The methodology considers four stages, namely: 1) selection of climatic drivers on a global scale, 2) processing of climatic drivers on a regional scale, 3) processing of design variables on a local scale and 4) application in different areas of infrastructure design. The methodology integrates the calculation of oceanographic variables (e.g. atmospheric pressure, wind, waves, astronomical tide, meteorological tide and sea level rise) in a flow diagram that can interact with other design variables, such as earthquakes and tsunamis. Examples are presented on calculations of port operational downtime, extreme sea levels on beaches, wave overtopping of maritime works and beach erosion. We encourage state agencies to develop stages 1) and 2), providing open access to stakeholders involved in the design of coastal and port infrastructure.
In this work, settlements results from measurements and from the numerical modelling of piled raft foundations are presented for an industrial structure under large loads. Due to the years of exploitation, it was needed to verify the settlements taken place in the raft, and the definitive values that can be reached. A numerical modelling is carried out to analyse the behaviour of the piled raft foundation under the action of the different combinations of loads. In addition, the validity of the model used is verified by comparison with measurements of displacements at the base of the foundation.
Analysis of the behaviour of a tuned mass damper considering uncertainty in the system parameters for high frequency content seismic excitations
The behaviour of a tuned mass damper is investigated when controlling a one degree of freedom system, when uncertainties of 5, 10 and 20% are included in the mass ratio of the AMS and the uncoupled translational period of the structure, in positive and negative sense with respect to the case of uncertainty. The excitation and analysis are of a stochastic type, and of high frequency content. To include uncertainty, a Taylor series expansion is used that considers only the first-order approximation. The range of mass ratios of the AMS ranges from 0.02 to 0.05, the periods of the structure cover a range from 1.5 to 2.0 s. The results show that the inclusion of uncertainty in the mass ratio and the period of the structure shows an influence on the values of the optimal parameters and on the efficiency of the AMS in reducing the standard deviation of displacement of the structure. Including uncertainty in the structure period shows the largest variations in optimal parameters and reductions. Uncertainties in system parameters have a notable influence and cannot be ignored. In general, the advantage of AMS tends to reduce or increase as the level of uncertainty increases in the positive or negative direction.
Study of the mechanical properties of masonry walls made with artisanal bricks with Vicia faba stem ashes
Bricks are considered one of the most used materials in construction since it is very required for building. Therefore, in this study the influence of handmade bricks with ash of Vicia faba stem on the mechanical properties of masonry walls is determined. For the study, two stages were carried out, the first consisted of the elaboration of masonry units with the addition of ashes in 0, 3, 6, 9 and 12% in relation to the weight of the clay with the farm ground. These samples were subjected to laboratory tests to obtain their physical and mechanical properties. Then for the second stage 30 piles and 15 walls were made, which were subjected to tests to obtain their mechanical properties. The maximum strength results were 45 kg/cm2 for axial compression, 12.6 kg/cm2 in flection and 8.3 kg/cm2 in shear. These values corresponds to 9% ash, taking this dosage as optimal and viable for the elaboration of artisanal bricks.
Estimation of the compressive strength of concrete at 28 days using Gaussian Mixture Models
The aim of this work is to estimate the compressive strength of concrete at 28 days using Gaussian Mixture Models. To carry out the work, a database of 82 dosages of different concretes and their maturity-resistance curves have been used. This database was populated with information obtained from the literature and completed with dosages carried out in the laboratory, which were monitored for 28 days. With this, a database was created with variables such as the water-cement ratio (W/C), the cement content and the temperature-resistance relationship over time. The aim is to estimate the 28-day resistance value of concrete used in Engineering and Construction, in a range of compressive strengths between 15 and 45 MPa. This is intended to numerically represent the behaviour of concrete maturity over time versus the increase in compressive strength. The Gaussian mixture regression GMR model allowed the estimation of compressive strength with an error of less than 13.54%.
A preliminary study for numerical representation of resonant column experiments in sand
This paper represents a collaborative effort utilizing the finite element method to simulate the resonant column (RC) apparatus. The aim is to explore how soil dynamic properties change with varying strain levels. The RC test, renowned for its ability to analyze soil behaviour under dynamic loads, is the focus of our study. However, accurate measurement of dynamic properties using the RC can be influenced by several factors, necessitating further investigation. These factors, including strain uniformity, base fixity, strain localization, topplaten coupling, sample shape, and soil uniformity, are the key areas of our research. To gain a deeper understanding of the effects of these variables on measured shear wave velocity and damping ratio, we performed finite element analysis using Abaqus/Explicit, a commercial finite element package based on continuum mechanics. The model was based on the specific RC setup configuration at the University of Waterloo. Initial parameters included the lowstrain properties of sand (shear modulus, Poisson’s ratio, damping ratio) with shear strain adjusted as a loading variable. Torsional loads were applied across shear strains from 10-5 to 10-4. The element size of the soil specimen mesh was varied to 25 mm, 10 mm, 7.5 mm, and 5 mm to observe its effect on the outcomes of the RC test. The finite element model analyzed the free vibration of the cylindrical sand sample post-forced vibration, assessing dynamic properties. Modal analysis of the RC configuration was performed to verify the primary influence of the first torsional mode. A Z-factor has been proposed as a multiplier of experimentally obtained damping ratio. Comparisons of damping ratios and resonant frequencies at various shear strains between finite element modelling and laboratory data demonstrate a strong correlation in the case of nonlinear shear strain, with differences firmly ranging from 0.50% to 3.5%.
Mechanical impedance evaluation of soils by variable energy dynamic penetration tests
Soil characterization by dynamic penetration testing (DPT) has been performed by establishing geotechnical parameters obtained from the application of correlations based on penetration indices, dynamic driving equations and to a lesser extent by direct measurements. This characteristic produces a decrease in the precision and variety of the geotechnical parameters that can be evaluated in the field by means of a DPT. To improve the accuracy in soil characterization, the evaluation of new geotechnical parameters based on measurements directly obtained in the penetration equipment is an alternative. The purpose of this paper is to present a methodology for the evaluation of soil mechanical impedance Zs by applying a decoupling and wave reconstruction method and to test the differentiating potential of this parameter between two different types of sands. Variable energy DPT tests were performed employing an instrumented penetrometer with strain sensors and accelerometer (PANDA3) on Hostun HN31 and Fontainebleau NE34 sand specimens reconstituted in dry state in a ko calibration chamber. The results showed that the evaluation of the mechanical impedance value in the two types of sands tested is possible by applying the decoupling method and reconstructing dynamic force and velocity signals at the cone-soil interface for each hammer impact on the dynamic penetrometer.
Main factors affecting the determination of the undrained strength of some Mexican soils by the field vane test
It is routine in geotechnical design practice to estimate the undrained strength of soils (su) using the CPTu test, based on correlations with laboratory tests. Correlations must be verified for each site with laboratory undrained triaxial tests on good quality undisturbed samples, which is a time-consuming and sometimes difficult activity. As an alternative approach, undrained strength can be determined more efficiently using the field vane shear test (VST). However, it should be noted that some adjustment to the standard rotation rate and/or correction to the μ factor may be required for particular soils. This paper presents experimental results on the influence of VST strain rate on the estimation of undrained shear strength. The test program was carried out on lacustrine soft clays from four sites in Mexico City (CDMX), where the water content varies from 100% to 500%, and experimental results from a tailings dam in northern Mexico are also presented. Undrained triaxial, VST and CPTu tests were performed on the CDMX soft clays. The rate of rotation varied from 0.1°/s to 4°/s to evaluate the peak, residual and remolded shear strength with VST. For the soft clay, the results show that the curve versus peak resistance has a minimum value in the range of 0.2 to 0.5, which is associated with the value of the undrained resistance of the soil without viscous phenomena. Therefore, for the clayey deposits of Mexico City, it is recommended to use this range of values to ensure that the correlations used in the piezocone are reliable. In terms of soil sensitivity, the results show that it decreases with increasing speed, with a smaller decrease at greater depths. For the tailings site, similar results to those found in Mexico City were observed, but VST tests using a rotation rate varying from 0.2 to 2°/s showed that the peak resistance has a minimum value at 1°/s.
Comparative study of P2PSand and Mohr-Coulomb constitutive models using FLAC3D for the seismic modeling of a tailings dam in Chile
The trend in the dynamic analysis of tailings deposits is to use advanced constitutive models in order to properly capture the cyclic behavior of the materials and thus have a better estimation of the physical stability of these structures. In this context, the main objective of this research is to compare the results of numerical simulations performed with a constitutive model used in current practice, such as the Mohr-Coulomb elastoplastic model, and an advanced constitutive model based on the critical state theory. This model, P2PSand, has the ability to represent the contractive and dilatant behavior of soils and the essential characteristics of the cyclic behavior of sands. From the results of the numerical analysis, the following conclusions can be drawn: P2PSand is able to adequately simulate the dynamic behavior of the sand in the tailing dam subjected to a measured earthquake of medium intensity (Mw = 5.4). P2PSand and Mohr-Coulomb constitutive models have the capability to analyze a maximum credible earthquake of magnitude 8.0 (Mw = 8.0), even if the earthquake is increased by 1.5 and 2 and if an advanced constitutive model is not used, the use of an elastic-plastic model with the addition of hysteretic damping is recommended.
Use of copper slag flotation tailings in concrete
This preliminary study explores the potential of copper slag flotation tailings (CSFW), a byproduct of the copper mining industry in Chile, as a partial replacement for Portland cement in concrete. A CSFW sample from a Chilean smelter was characterized, and concrete mixtures with CSFW substitutions ranging from 0% to 20% (in 5% increments) were tested to evaluate compressive strength at 7, 28, and 60 days. X-ray diffraction (XRD) revealed that CSFW is primarily composed of hedenbergite, magnetite, fayalite, and albite. Although compressive strength decreased with higher levels of CSFW substitution, the mixture with 5% replacement achieved approximately 80% of the control concrete’s strength at 60 days. Plasticity increased significantly with CSFW content, with slump tripling in the 20% mixture compared to the control, which indicates an increase in workability but also an excess of water in the mix. These results suggest that CSFW is a viable alternative for low-level cement replacements, promoting the valorization of mining waste and environmental sustainability in the construction sector in Chile.
Prediction of moisture content of soils for the sub-base layer using experimental simulation in a climatic chamber
An adequate soil moisture content allows the soil to reach its maximum density when compacted, improving soil cohesion and stability. In some soils, the optimal moisture content is lower than the natural moisture content, which requires its reduction through exposure outdoors. However, this desiccation is seasonal, being lower in mid-season months. Determining the soil desiccation rate in each season allows for planning road construction and ensuring the availability of soil with optimal moisture. This work presents a procedure for predicting soil moisture reduction through experimental simulations in a climatic chamber, considering temperature, relative humidity, wind speed, and solar radiation. The results allow for efficient and sustainable planning of earthworks, optimizing the reuse of excavated soil in road infrastructure projects and contributing to the reduction of environmental impact and costs.
Nonlinear stress-strain model for the gravel of Santiago
In this work a study on the stress-strain behaviour of the Santiago gravel deposited by the Mapocho river is presented. Results from field Irials are briefly described and they are compared with results obtained from a developed non-lineal constitutive model. There was a remarkable agreement between measured and calculated results. From that it was possible to conclude that thanks to the achievements of Geotechnical Engineers from industry, it was possible to collecta valuable experimental database which allowed the development of a powerful numerical model. This model is able to estimate with accuracy the displacements of the Santiago gravel when external loads are applied or when excavations on the surface or underground, studied in elastic as well as non-elastic regime, are carried out.
Preliminary feasibility study of concrete with metallic fibres from end-of-life tires for selfheating pavements
This research explores alternatives to industrial metal fibres (IMF) used in concrete, proposing their replacement with metal fibres from end-of-life tires (ELTF) and steel shavings (SS). The objective is to analyse the effects of incorporating ELTF on the mechanical and physical behaviour of concrete intended for self-defrosting pavements. Tests indicate that the 1.5% IMF + 13.5% SS mixture exhibits compressive strength equivalent to that of conventional concrete, while the 1.5% IMF + 13.5% SS mixture shows a 25.9% decrease compared to the control, attributed to the presence of contaminants. However, superior thermal performance is observed in the mixture with ELTF, which demonstrates 3.4 times greater efficiency in increasing internal temperature compared to the mixture incorporating IMF. Taken together, these results suggest opportunities for innovation in the concrete industry, showing that the use of recycled materials such as FMNFU can contribute not only to reducing costs and the carbon footprint, but also to improving the thermal performance of pavements.