Abstract:This study aims to develop a final design for the Northwest Slope of the Cuajone Mine (Peru) by calculating the factor of safety (FS) using finite element methods, proposing that this method enables a more accurate assessment of slope stability. The methodology included geological and geotechnical characterization of the slope through field mapping, sample analysis, and laboratory testing. A three-dimensional model was created using Phase2 software to simulate the interaction between slope geometry and operational conditions, conducting a stability analysis under different loads and disturbances. The results indicate that the finite element method detailedly evaluated the safety factor and the inter-ramp angle (IRA). In the southern zone (section A-A'), it was determined that an IRA of 43° generates an FS of 1.1. In the northern zone (section B-B'), an IRA of 38° is recommended to achieve an FS of 1.57. These findings are essential for ensuring operational safety and efficiency at the mine, as an inadequate slope design could compromise infrastructure integrity and worker safety. Advanced methods, such as finite element analysis and considering factors like IRA and disturbance factors, allow for a precise slope stability assessment and effective stabilization measures to manage risks and develop specific reinforcement solutions according to the slope's geotechnical configuration.

Resumen: El objetivo de este estudio es desarrollar un diseño final para el Talud Noroeste de la Mina Cuajone (Perú) utilizando el cálculo del factor de seguridad (FS) mediante métodos de elementos finitos, planteando que este método permite una evaluación más precisa de la estabilidad del talud. La metodología incluyo la caracterización geológica y geotécnica del talud mediante mapeo de campo, análisis de muestras y pruebas de laboratorio. Se creo un modelo tridimensional usando el software Phase2 para simular la interacción entre la geometría del talud y las condiciones operativas, realizando un análisis de estabilidad bajo diferentes cargas y perturbaciones. Los resultados indican que el método de elementos finitos proporciono una evaluación detallada del factor de seguridad y del ángulo interrampa (IRA). En la zona sur (sección A-A'), se determina que un IRA de 43° genera un FS de 1.1. En la zona norte (sección B-B'), se recomienda un IRA de 38° para lograr un FS de 1.57. Los hallazgos son fundamentales para garantizar la seguridad y eficiencia operativa en la mina, ya que un diseño de talud inadecuado podría comprometer la integridad de la infraestructura y la seguridad de los trabajadores. La aplicación de métodos avanzados como el análisis de elementos finitos y la consideración de factores como el IRA y el factor de perturbación permite una evaluación precisa de la estabilidad del talud y la implementación de medidas de estabilización efectivas para gestionar los riesgos y desarrollar soluciones de refuerzo específicas según la configuración geotécnica del talud.

One of the consequences of large-scale opencast mining for coal is the disposal of an enormous volume of overburden material that needs to be removed. With the enlargement of opencast mines and associated high stripping ratios, the volume of overburden extraction is rising. Overburden from the initial mine cut has to be necessarily dumped outside the mining area until enough void is created inside the mine for back-filling operations. The quantity of overburden placed outside the mining area normally varies from 10% to 30% of the total overburden removal. The stability of these dumps placed outside the mining area is of prime importance from the point of view of smooth operations of the mines and safety of persons in and around the dumping area. Owing to increasing pressure on land use, mine operators do not have any other option other than to place the waste dumps very near to the surface edge of the pit, which may lead to failure of the topsoil benches of the working pit. This study identified major controlling parameters that influence a stable but economic combination of height and slope angle of external dumps located close to the edge of an open coal pit.

Abstract: Rapid drawdown has been identified as one of the most frequent causes of slope failures due to the effects associated with drought and operational changes when incorporating hydroelectric plants, which influence the filling level of earth dams. The main goal of this research is to obtain predictive models based on Artificial Neural Networks that return the factor of safety of the upstream slope in homogeneous earth dams in the face of the effect of rapid drawdown. Three geometries and 40 soils were defined to form the embankment, from which hybrid numerical models of transient water flow with unsaturated soils were built, considering three discharge speeds. From these results, a database was built to develop the predictive models, by means of the KNIME program and an algorithm based on Artificial Neural Networks. The behavior of the factor of safety as a function of time is also analyzed to establish its recovery intervals. Main results show that the minimum factor of safety is obtained between 52 % and 88 % of the total drawdown time. Regarding the predictive models, the adjusted R2 determination coefficients were greater than 95 % in all cases and the errors remained below 10 %. This demonstrates a high effectiveness of this algorithm and the validity of its application to geotechnical problems.

Resumen: El desembalse rápido se ha identificado como una de las causas más frecuentes de las fallas en taludes debido a los efectos asociados a la sequía y a los cambios de operación al incorporar hidroeléctricas, los cuales influyen en el nivel de llenado de las presas de tierra. Esta investigación tiene como objetivo fundamental la obtención de modelos predictivos basados en Redes Neuronales Artificiales que devuelvan el factor de seguridad del talud aguas arriba en presas de tierra homogéneas ante el efecto del desembalse rápido. Se definieron tres geometrías y 40 suelos para conformar el terraplén, a partir de los cuales se construyeron modelos numéricos híbridos de flujo de agua transitorio con suelos no saturados, considerando tres velocidades de desembalse. A partir de estos resultados, se construyó una base de datos para desarrollar los modelos predictivos, a través del programa KNIME y un algoritmo basado en Redes Neuronales Artificiales. Se analiza, además, el comportamiento del factor de seguridad en función del tiempo para establecer sus intervalos de recuperación. Los principales resultados muestran que el factor de seguridad mínimo se obtiene entre el 52 % y el 88 % del tiempo total de desembalse. En cuanto a los modelos predictivos, los coeficientes de determinación R2 ajustados fueron superiores al 95 % en todos los casos y los errores se mantuvieron por debajo de 10 %. Se demuestra una alta efectividad en este tipo de herramienta y la validez de su aplicación a problemas geotécnicos.

The selection of open-pit slope angles involves high-value decisions with small changes in slope angle, often representing significant changes in net present value. The existing methods used to define design acceptance criteria have evolved from factor of safety to probability of failure (P[F]) to risk consequence to risk frontiers, which represents current state of the art. Current design acceptance measures are based on references to published tables representing the experience and judgement of their authors, who did not specify the purpose of the measures contained therein. As the purpose of the published design acceptance criteria is not specified (i.e., definite stability, marginal stability, optimization, etc.), such tables cannot be used to achieve optimum slope angles that maximize profitability. This paper develops a design acceptance criterion that maximizes profitability by defining a formulation for optimum risk that balances expected risk and reward. The model developed is titled the Mining Risk Model (MRM), and is applied to open-pit slope angle selection through an equation for optimum probability of downside (P[£)]O) that balances the upside or opportunity, the P[F], and the downside impact. This formulation for optimum risk is unique, as many authors have presented objective functions for their risk models that can be optimized, but none of the sources reviewed contained a formulation for optimum risk. The MRM is sufficiently flexible to allow the design performance measure that drives P[F], and hence P[D] O, to be selected based on the intended goal. Furthermore, the essential information that must be known to quantify optimum risk is defined. This allows users to determine what information to collect for optimum risk decisions. A further benefit of the MRM is that slope angle decisions and pit shells can be ranked to select the best option, and a threshold is provided that separates acceptable from unacceptable decisions. Finally, the workflow and information required to determine optimum risk are presented.

Abstract: The main objective of this study is to estimate the safety factors and the probability of planar failure in the slopes of the Comuna Universitaria of the city of Manizales (Colombia). Geotechnical data gathered over a period of 14 years is processed statistically. The infinite slope equation is applied through Monte Carlo simulations to assess typical input scenarios including cohesion, friction angle, groundwater level, and inclination of layers with the presence of ash and anthropogenic fills. The simulation involved 5000 iterations for each variable, resulting in a tool for detecting conditions causing instability in the slopes of the Comuna Universitaria. It is concluded that for acceptable safety factors calculated deterministically, it is possible to obtain high risk levels with relation to failure probability function, making probabilistic analyses conservative and useful for early warning detection.

Resumen: El principal objetivo del presente estudio es estimar los factores de seguridad y la probabilidad de falla planar en los taludes de la Comuna Universitaria de la ciudad de Manizales (Colombia). Se realiza un procesamiento estadístico de los datos recolectados durante 14 años de estudios geotécnicos. Se aplica la ecuación de talud infinito en una simulación de Monte Carlo para analizar escenarios típicos de entrada como cohesión, ángulo de fricción, nivel de aguas freáticas e inclinación de estratos con presencia de ceniza y llenos antrópicos. En la simulación se generan 5000 iteraciones para cada variable, obteniendo como resultado la representación de una herramienta para detección de condiciones que generan inestabilidad en los taludes de la comuna. Se concluye que para factores de seguridad aceptables calculados por métodos determinísticos, se pueden tener niveles de amenaza altos en función de probabilidad de falla por lo que los análisis probabilísticos se consideran conservadores y útiles en la detección temprana de desastres.

The placement of boulders in streams enhances aquatic habitat by increasing the heterogeneity of flow conditions. Practical design must ensure the stability of individual boulders, requiring calculation of their incipient movement conditions. The stability of a boulder on a cobble bed is shown experimentally to depend on its size, the bed material size, the degree of embedment of the boulder, the slope of the bed and the flow velocity and depth. An equation is derived through a pivoting analysis for predicting the relationship between the critical ambient depth-averaged velocity and the critical flow depth; this, together with a resistance equation, can be used to predict the flow conditions for boulder stability. The equation is used to develop a simpler form for unsubmerged spherical boulders and cobbles. The stability equation is tested against the experimental data, using an experimentally determined drag coefficient relationship.

Resumen Dentro de las estructuras de retención o contención, usadas ampliamente en la infraestructura vial, existe una gama amplia de posibilidades, como son las estructuras de gravedad convencionales (gaviones, criba, etc.), reforzadas, embebidas, anclajes, suelo estabilizado mecánicamente, entre otras. Dentro de ellas también, se encuentran las bolsas gigantes de geotextil, las cuales funcionan por gravedad usando material de relleno del sitio y demostrando un buen rendimiento ante la protección contra la erosión fluvial, marítima y en obras de protección o de contención para vías. Este artículo presenta la versatilidad de las bolsas gigantes de geotextil en la infraestructura vial, en la estabilización de terraplenes, taludes; y control de erosión fluvial y costera. Se presenta como estudio de caso a la zona de Bengala (kilómetro 21 de la vía Garzón - Neiva) y Túnel de Crespo (Cartagena - Colombia). La metodología utilizada para evaluar la evolución de la mejora con la intervención de bolsas gigantes de geotextil se realiza mediante el reporte de diseño, ejecución, seguimiento y control de la geometría del sitio de estudio. Las zonas intervenidas con bolsas de geotextil gigante presentan un comportamiento efectivo en la estabilidad del terreno, en el control de erosión y en la recuperación geométrica. A nivel cualitativo se logra evidenciar el proceso de restauración y estabilización de la costa y talud afectados, gracias a la intervención con bolsas de geotextil gigantes. A nivel cuantitativo se aprecia la estabilidad a largo plazo y la recuperación geométrica de las zonas intervenidas.

Abstract Between retaining structures, widely used in road infrastructure, there is a wide range of possibilities: conventional gravity structures (gabions, screens, etc.), reinforced, embedded, anchors, mechanically stabilized soil, among others. Among them, there is also the giant geotextile bags, which work by gravity using fill material from the site and demonstrating good performance against fluvial and maritime erosion, and road protection or containment. This article presents the versatility of giant geotextile bags in road infrastructure, embankment or slope stabilization; and river and coastal erosion control. As a case study, the Bengala (kilometer 21 of the Garzón - Neiva road) and Crespo Tunnel (Cartagena - Colombia) are presented. The methodology used to evaluate the evolution of the improvement with the intervention of giant geotextile bags is done through the report of design, execution, follow-up and control of the geometry of the intervened site. The areas intervened with giant geotextile bags show an effective behavior in soil stability, erosion control and geometric recovery. At a qualitative level, the process of restoration and stabilization of the affected coast and slope is evident, thanks to the intervention with giant geotextile bags. At a quantitative level, the long-term stability and geometric recovery of the intervened areas can be appreciated.

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.

Resumen En México los desastres naturales relacionados con sedimentos, como los desprendimientos, deslizamientos y aluviones, generalmente son inducidos por actividades antropogénicas como la construcción de caminos, que modifican, la cubierta vegetal, características del suelo, la densidad de las raíces y la estabilidad de los taludes. El objetivo de esta investigación fue evaluar las características mecánicas y químicas de raíces de especies forestales arbóreas (J. deppeana, Q. sideroxyla, P. durangensis y P. cooperi) presentes en cortes de talud de la carretera principal que conecta la zona urbana con la zona rural del municipio de Pueblo Nuevo, Durango. Se colectaron 30 muestras de raíces por especie y fueron divididas en tres categorías diamétricas (CD) (CD I = 0.1-3.0 mm, CD II = 3.1-6.0 mm y CD III = 6.1-10 mm). Las propiedades mecánicas (fuerza máxima de quiebre [Fmax], fuerza de tensión [Ts] y módulo de elasticidad [Eroot]) se analizaron con una maquina universal Instron SATEC a una velocidad constante de 10 mm/min. La cantidad de celulosa, lignina y hemicelulosa se determinó por medio del método de Van-Soest. Los resultados mostraron diferencias significativas entre especies para todas las propiedades analizadas. Particularmente J. deppeana presentó valores más altos de Fmax, Ts y Eroot de 402.80 N, 34.06 N mm2, 1283.45N mm2, así como de los contenidos de celulosa (40.29%), hemicelulosa (12.57%) y lignina (37.63%). La caracterización mecánica y química de las raíces de las especies forestales evaluadas provee información importante que puede ser considerada en actividades de mantenimiento y rehabilitación de taludes.

Abstract In Mexico, natural disasters related to sediments, such as landslides, landslides and alluviums, are generally induced by anthropogenic activities such as road construction, which modify the vegetation cover, soil characteristics, root density and soil stability. slopes. The objective of this research was to evaluate the mechanical and chemical characteristics of roots of tree forest species (J. deppeana, Q. sideroxyla, P. durangensis y P. cooperi) present in slope cuts of the main road that connects the urban area with the rural area of the municipality of Pueblo Nuevo, Durango. 30 root samples per species were collected and divided into three diameter categories (CD) (CD I = 0.1-3.0 mm, CD II = 3.1-6.0 mm and CD III = 6.1-10 mm). The mechanical properties (maximum breaking force [Fmax], tensile strength [Ts] and elastic modulus [Eroot]) were analyzed with an Instron SATEC universal machine at a constant speed of 10 mm/min. The amount of cellulose, lignin and hemicellulose was determined using the Van-Soest method. The results showed significant differences between species for all the properties analyzed. Particularly J. deppeana presented higher values of Fmax, Ts and Eroot of 402.80 N, 34.06 N mm2, 1283.45 N mm2, as well as the contents of cellulose (40.29%), hemicellulose (12.57%) and lignin (37.63%). The mechanical and chemical characterization of the roots of the evaluated forest species provides important information that can be considered in slope maintenance and rehabilitation activities.

Abstract Rock and joint alteration leads to modifications in their properties, resulting in a reduction of rock mass strength and consequently a decrease in the safety of engineering structures. The alteration process changes the material and alters its geomechanical behavior. This research presents the studies conducted to evaluate the mechanical behavior of rock joints in the gneiss massifs that make up the hydraulic circuit of the Simplicio Hydroelectric Plant due to their alteration. Compilation and analysis of data from previous research were carried out to parameterize the joints at different levels of alteration. Deterministic stability analyses showed that the alteration process of gneiss joints can significantly reduce the slope safety factor by up to half of its initial value. Furthermore, probabilistic analyses revealed an increase in failure probability of approximately 10% among the studied alteration classes. The results underscore the importance of assessing the level of joint alteration in engineering projects.

Abstract As opencast coal production increases, a crucial challenge is safeguarding the stability and management of overburden dumps while prioritizing both safety and cost-efficiency. Determining the optimal stable dump slope dimensions during and after mining remains a key challenge for mining operations worldwide. Assessing the stability of overburden (OB) dumps is necessary to maintain them at the steepest possible angle without compromising stability. Understanding the shear strength, including cohesion and angle of internal friction, of the heterogeneous dump mass is crucial for this assessment. To evaluate the shear strength behaviour of OB materials, a large direct shear machine (LDSM) was designed and developed at Central Mine Planning and Design Institute, Ranchi. The LDSM features a shear box with dimensions of 1000 mm × 1000 mm × 1000 mm to facilitate testing materials with larger particle sizes. It can test large specimens with a thickness up to 500 mm and a maximum particle size (Dmax) of 80mm in accordance with ASTM D3080-98. Seven different OB materials from Magadh Coalfields, India were collected and tested for their shear strength. Using the obtained shear strength parameters, various slope profiles are assessed for stability using 2D limit equilibrium software such as Slide2 and GALENA. Probabilistic modelling is employed to generate a statistically distributed factor of safety (FoS) instead of a deterministic value, accounting for uncertainties related to input parameters. This paper aims to forecast the maximum safe height for OB dumps based on the determined shear strength parameters.

Abstract The residual tropical soils and their unsaturated condition add more complexity to the study of slope stability, introducing the suction variable to the stress state analysis. Due to the complexity of the pedological processes involved in their formation, tropical soils present variability in their parameters. This results in uncertainties regarding its behaviour in geotechnical structures. The most common promotion agent for deformation and loss of strength in residual soils in an unsaturated condition is the advancing of the wetting front due to rainfalls. A tropical climate with high levels of rainfall makes landslides a constant and dangerous phenomenon, leading to loss of human life and material. Thus, it is essential to verify the influence of precipitation on slope behaviour in residual conditions. This study analyzes the behaviour of a slope formed by a residual soil by determining the soil properties followed by a numerical analysis. Laboratory tests were performed to characterize the soil and determine the strength, hydraulic, and unsaturated condition parameters. In the numerical analysis, it was intended to visualize the influence of rainfall and hydraulic parameters on the pore pressure distribution inside the slope and in its stability. After the numerical step, it was found that the different rainfall characteristics (intensity and duration) increased the pore pressures and decreased the strength of the material. However, it was insufficient to trigger any failure mechanisms. The hydraulic parameters’ critical roles at seepage through the soil and how this is reflected in the calculations of safety factors were verified.

Abstract Some foundations are placed on or near slopes or excavations, such as roads in mountainous areas, tower footings for power lines, and bridge abutments. The design of foundation under these conditions is complex and the studies available in this regard are limited and concerned mostly about the determination of the reduction of the bearing capacity coefficients associated with the presence of the slope except for Meyerhof who was a pioneer in developing a theory in 1957 to determine the ultimate bearing capacity of a foundation near a slope. However, the theory was independent of the slope inclination. In this study, we attempted to numerical modeling of the behavior of a shallow foundation using the finite element technique together with Plaxis 8.2 software to simulate the case of a foundation near a slope, in terms of examining the bearing capacity of the foundation for given slope features, soil characteristics and geometry conditions located near a slope subjected to a centered and / or eccentric load. The results obtained confirm that the position of the eccentricity of the load relative to the head of the slope has a significant effect on the bearing capacity. Indeed, it becomes larger when the eccentricity is located far from the crest of the slope. Thus, the bearing capacity of a footing subjected to a centered load (e/B = 0) is greater than that of the same footing subjected to an eccentric load (e/B = 0.1). It is noted that the results obtained from the present study are in good agreement with those of the literature.

Abstract This article presents the incorporation of information and communication technologies on the teaching-learning process of geotechnical engineering to improve the quality of education and provide practical knowledge to civil engineering students. The content of this paper is divided into three main modules, which are: Treatment of laboratory tests results, Slope stability and Rock mass stability. For this, some software were used, including 2D limit equilibrium stability analysis, stability analysis of rock wedges and a dynamic mathematics, to obtain and analyze soil shear strength parameters, among others. Furthermore, a digital tool was developed to analyze the results gathered in compaction, one-dimensional consolidation, and direct soil shear tests, in order to clarify the relationship between theoretical concepts and practical results of the tests and analyses and to help students on doubts, in addition to increase their interest and motivation to perform the complete interpretation of the collected data. The activities were conducted in classes of geotechnical disciplines of the undergraduate course in Civil Engineering at the Federal University of Viçosa, aiming to promote active learning and improve teaching quality. Based on the results of an applied feedback questionnaire, it was observed that most students were satisfied with the resources used in the classroom, demonstrating that the implemented digital tools work as a didactic instrument that facilitates learning and comprehension of practical problems, in addition to enabling the resolution of several geotechnical engineering problems much more quickly and efficiently.

Abstract The state of Espirito Santo is the most important producer and exporter of ornamental quarry stone. In its various quarries, it uses bench heights that range from 5, 20, 50 and 100 meters. The high altitudes raise concerns about the stability of the slopes. Therefore, the study focuses on determining the value of the safety factor (SF) for these heights using the limit equilibrium method. To make this possible, the values of simple uniaxial compression, Geological Strength Index (GSI), the disturbance factor, and intact rock parameter must be obtained. To obtain the GSI, it is necessary to establish a correlation with the Rock Mass Rating, the values of which are determined using a scan line. The uniaxial compression values were treated statistically, obtaining classes at 75, 100, 125, 150, 175, and 200 Mpa. The 2D slide software was used to obtain the SF values for the respective heights. With the results obtained, these rocks do not present stability problems. The correct choice of GSI is of paramount importance for a good analysis, as it directly affects the results. Using this technique to determine safety factors is appropriate, but it is necessary to analyze more robust methods to compare the results.