Minimum Safety Factor Research Articles

Risk assessment of a glacial lake with abruptly slowing expansion, Jiongpu, Southeastern Tibet

The expansion of potentially hazardous glacial lakes is a symptom of global warming during this interglacial period. A pertinent example is the Jiongpu glacial lake in southeastern Tibet, the area of which has expanded approximately fivefold in the last half-century. However, recently, the glacier tongue has retreated to a high steep slope, and the rate of retreat of the glacier and expansion of the lake have temporarily slowed. The risk of a glacier tongue landslide after glacier detachment and subsequent glacial lake outburst flood (GLOF) needs to be assessed. In this study, we employed a combination of unmanned aerial vehicle (UAV), sonar, geological radar, remote sensing, field investigation, sampling, drilling, and dating techniques to determine the critical parameters of potential GLOFs, including glacier tongue geometry, lake bathymetry, and moraine dam geometry and composition. Utilizing empirical models and multiphase flow models, we identified the most hazardous triggers and simulated the processes of a glacier tongue landslide into the lake, moraine dam overtopping by a displacement wave, and subsequent flood evolution. The results showed that the most hazardous trigger in volume is a glacier tongue landslide, accounting for 58.29 % of all triggers associated with potential GLOFs. Lapped by the largest glacier tongue landslide impulse wave, the moraine dam would not fail because the minimum safety factor is approximately 1.66 ± 0.7 according to empirical methods and geological slope simulation. However, overtopping would occur, resulting in a peak discharge of approximately 9740 ± 4137 m3/s at the moraine dam based on r.avaflow calculations. The flood would reach the densely populated Jinling township and inundate approximately 46 ± 4.55 % of the houses according to HEC-RAS. Reducing the water level of the glacial lake represents an effective strategy for mitigating potential losses. This concise, physics-based method effectively assesses GLOF triggers and processes and can be applied to risk assessments of other expanding glacial lakes.

Design and Finite Element Analysis of a Thresher for Palm Oil (Elaies guineensis) Extraction Plant

This study presents the design and Finite Element Analysis (FEA) of a thresher used in palm oil (Elaeis guineensis) extraction plants. The FEA was performed to ensure safe and cost effective of the thresher before fabrication. The analytical design of the threshing shaft and drum of the thresher was validated using SolidWorks (2021) CAD software for static simulation, employing plain carbon steel as the material. For the threshing shaft, forces of and were applied at strategic points, resulting in a maximum bending stress of , significantly below the yield strength of . The shaft's diameter of 50 mm was confirmed as adequate with a factor of safety (FOS) ranging from 3.17 to 142.42, validating the shaft design's safety for fabrication. Similarly, the drum unit, supported by a spider arm and cylindrical bars, was subjected to an equivalent twisting moment of 861.25 Nm and a batch weight of 1226.25 N. The maximum von Mises stress of was well within safe limits, indicating robustness under operational loads. The maximum resultant displacement and equivalent strain were respectively which can be said to be minimal, reinforcing the drum's structural integrity. A minimum FOS of 20.45 further highlighted the drum's durability and resistance to fatigue. These results confirm the reliability and safety of the designed thresher components, ensuring efficient and sustainable palm oil extraction.

Artificial Neural Network Model to Predict the Factor of Safety in Earth Dams Subjected to Rapid Drawdown

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.

An Analysis of the Slope Stability of Young Rock Cliffs in Sibang, Bali Using GEO5

This study presents a comprehensive analysis of slope stability for young rock cliffs in the Sibang region of Bali, employing advanced geotechnical software GEO5. The investigation is crucial due to the dynamic geological conditions and rapid changes in land use in the area, posing potential risks to infrastructure and environmental stability. The research focuses on young rock cliffs, characterized by recent geological formations, which are inherently susceptible to slope instability. This slope stability analysis is carried out using the GEO5 auxiliary program which will produce a Safety Factor value which is used as the basis for building a construction which interprets whether the slope is safe or not. The safety factor value used as the minimum value is 1.5, so the slope must have a SF value ≥ SF min = 1.5. This analysis was carried out on 4 cross sections with 2 method which name is Morgenstern-Price and Bishop Method because the analysis carried out was complex in terms of force and moment. The Safety Factor of cross section on BH-03 to BH-01 is not safe because the value is 1,16 and 1,15 which is < 1,5 (the minimum safety factor). Therefore, the slope must modelled with terraced slopes and also retaining wall reinforcement for each modelled terrace height.

Seismic Safety Evaluation of Mechanically Stabilized Earth (MSE) Wall for Highway Construction

The usage of Mechanically Stabilized Earth (MSE) Walls has grown in popularity over the last few decades and has been widely used in many countries for highway construction, including Indonesia. As a country with a high risk against seismic hazards, a considerable stability analysis against earthquakes for construction must be conducted. This paper is directed to evaluate the static and seismic stability of MSE wall by adopting design criteria from SNI 8460:2017 using the pseudo-static approach with Limit Equilibrium Method (LEM) which modelling earthquake as a seismic coefficient, a one-way constant load and dynamic response approach with Finite Element Method (FEM) which modelling earthquake as ground motion, a fluctuating load which varies in time. The stability analysis is performed by considering three failure mechanisms that mostly occurred in MSE Walls; base sliding, tensile overstress, and slope failure. The earthquake load is modelled based 1000-year return period earthquake. Based on the analysis result, the most potential failure mechanism that may occur in the MSE wall is tensile overstress, while the least potential failure is base sliding. The analysis result also shows that the finite element method obtained higher safety factors compared to limit equilibrium, while on the other hand, the remaining two failure mechanisms shows the different result, with the finite element method obtaining lower safety factors than limit equilibrium. Modelling seismic load as an accelerogram indicates that earthquakes have higher impacts on structure stability compared to seismic coefficient, based on seismic safety factor reduction of each method. Although show differences in the value of the safety factor, the minimum safety factor required still complies with both methods.

Structural integrity assessment of a solid propellant grain considering confining pressure effect

Confining pressure has a significant effect on the mechanical properties of solid propellant, and it is crucial to develop a refined structural integrity analysis and assessment method considering confining pressure effect and nonlinearity of propellant material for the design of propellant grain of a solid rocket motor (SRM), especially for the design of high charge modulus. In this work, an existing viscoelastic-viscodamage constitutive model considering confining pressure effect was implemented as a user-defined material subroutine and verified using a few experiments under various confining pressures. The mechanical responses and safety factor of a typical variable cross-section propellant charge SRM with various charge modulus under ignition pressurization load and room temperature were analyzed and evaluated. The results show that the user-defined material subroutine can well describe nonlinear mechanical responses of solid propellant under different experimental conditions. The Von Mises stress and minimum safety factor considering the confining pressure effect are higher than the value without considering the confining pressure effect, while the Von Mises strain is opposite. In addition, regardless of whether the confining pressure effect is considered or not, the maximum Von Mises stress and strain show a nonlinear increasing relationship with the charge modulus, and the minimum safety factor decreases with charge modulus. However, when analyzing the structural integrity of high charge modulus, using two evaluation methods will yield completely different evaluation results. It is believed that this research can support structural integrity analysis and design of high charge modulus SRM.

Grasshopper platform-assisted design optimization of fujian rural earthen buildings considering low-carbon emissions reduction

This work aims to explore optimization methods for the design of earthen buildings in rural Fujian to achieve low-carbon emissions and improve the structural stability of earthen buildings. First, parametric modeling and optimization algorithms are employed through the Grasshopper platform. An intelligent earthen building design is created by combining the optimization of factors such as the structure of earthen buildings, building materials, and orientation. Then, a comparison is made with the unoptimized, energy-efficient, and carbon emission reduction designs. Finally, the work concludes that the proposed design significantly optimizes the total carbon emissions, energy consumption, structural stability, and economic aspects. The proposed design scheme achieves the highest carbon emission reduction effect, with a reduction rate of 34.64%. The proposed design exhibits lower maximum stress and higher minimum safety factor in terms of structural stability compared to other scenarios, along with smaller structural displacement. It also performs well in terms of initial investment, annual operating costs, and construction period. The significance of this work lies in providing scientific guidance for the design and construction of rural earthen buildings, promoting the organic integration of rural development with low-carbon initiatives. This indicates that the use of intelligent optimization methods for earthen building design is feasible and can yield positive results in practice.

Seismic Stability Study of Bedding Slope Based on a Pseudo-Dynamic Method and Its Numerical Validation

Earthquakes are one of the main causes of bedding slope instability, and scientifically and quantitively evaluating seismic stability is of great significance for preventing landslide disasters. This study aims to assess the bedding slope stability under seismic loading and the influences of various parameters on stability using a pseudo-dynamic method. Based on the limit equilibrium theory, a general solution for the dynamic safety factor of bedding slope is proposed. The effects of parameters such as slope height, slope angle, cohesion, internal friction angle, vibration time, shear wave velocity, seismic acceleration coefficient, and amplification factor on stability are discussed in detail. To evaluate the validity of the pseudo-dynamic solution, the safety factors are compared with those given by early cases, and the results show that the safety factors calculated by the present formulation coincide better with those of previous methods. Moreover, a two-dimensional numerical solution of bedding slope based on Mohr–Coulomb’s elastic–plastic failure criterion is also performed by using the finite element procedure, and the minimum safety factor is essentially consistent with the result of the pseudo-dynamic method. It is proved that the pseudo-dynamic method is effective for bedding slope stability analyses during earthquakes, and it can overcome the limitations of the pseudo-static method.

Nature-inspired optimization prey–predator algorithm for soil slope stability analysis with physically informed initial population generation

In soil slope stability, locating the critical slip surface with the minimum safety factor is a difficult and complicated optimization problem. Most methods fail when proper bounds are not applied to the decision variable. For the first time, the paper uses the prey–predator algorithm to analyze slopes stability with circular slip surfaces making use of meaningful rules, from an engineering point of view, to define these bounds. The Fellenius method based on limit equilibrium technique also serves as the constraint of the mathematical problem adopted to solve the task. A pseudo-analytical study is also carried out on four benchmark literature problems to test the performance and to certify the accuracy of the results obtained with the new application of the prey–predator algorithm. We show that the solutions obtained are accurate and should be assumed as a reference comparing to other methods.

Seroja Tropical Cyclon Destruction Case Study: Permanent Slope Protection Evaluation at Downstream of Rotiklot Dam Nomenclature Building, East Nusa Tenggara, Indonesia

Abstract Rotiklot Dam was one of some infrastructures which was affected by the Seroja Tropical Cyclone in East Nusa Tenggara Indonesia in April 2021. There are several landslides at the downstream of the dam that can threaten the safety of the dam, especially at the downstream of the nomenclature building. The right design of permanent slope protection must be determined in a limited time. Geotechnical investigations such as boring, resistivity survey, standard penetration test, and water pressure test were conducted in a short time. Back analysis method was carried out to find extreme soil parameters conditions. The slope protection must meet the national standard minimum safety factor or greater than 1.5. Safety factors of slope protections are evaluated by a finite element method to get the safety factor and maximum total displacements. Every stage of slope protection can give the optimal safety factor values which are required or greater than 1.5, however backfill material will give more load and decrease the safety factor value.

Reservoir Slope Stability Analysis under Dynamic Fluctuating Water Level Using Improved Radial Movement Optimisation (IRMO) Algorithm

External water level fluctuation is the major trigger causing reservoir slope failure, and therefore it is of great significance for the safety assessment and corresponding safety management of reservoir slopes. In this work, the seepage effects stemming from fluctuating external water levels are given special analysis and then incorporated into the rigorous limit equilibrium method for assessing the stability of reservoir slope. An advanced metaheuristic intelligent algorithm, the improved radial movement optimisation (IRMO), is introduced to efficiently locate the critical failure surface and associated minimum factor of safety. Consequently, the effect of water level fluctuation directions, changing rates, and soil permeability coefficient on reservoir stability are investigated by the proposed method in three cases. It is found that the clay slope behaved more sensitively in stability fluctuation compared to the silty slope. With the dropping of external water, the higher dropping speed and lower soil permeability coefficient have worse impacts on the slope stability. The critical pool level during reservoir water dropping could be effectively obtained through the analysis. The results indicate that the IRMO-based method herein could effectively realise the stability analysis of the reservoir slope in a dynamic fluctuating reservoir water level, which could provide applicable technology for following preventions.

Optimization design of battery bracket for new energy vehicles based on 3D printing technology

Nowadays, what captures consumers' primary attention is how to purchase electric vehicles with long range and desirable price. Lightweight construction stands as one of the most effective approaches for prolonging range and lowering costs. As a consequence, it is particularly imperative to undertake lightweight design optimization for the battery bracket of new energy vehicles by applying 3D printing technology. To actualize this goal, Rhino software was initially employed for 3D modeling to design the battery bracket system for a pure electric vehicle in China. Subsequently, topology optimization design of the battery bracket was carried out by adopting Altair Inspire software. Last but not least, manufacturing and assembly inspection were completed using a 3D printer. The results show that the maximum displacement of the battery lower tray bracket after topology optimization is 3.20 mm, which is slightly higher than before, but still relatively small. The maximum Mises equivalent stress rose to 240.7 MPa post-optimization, but brought about a uniform stress distribution at the bottom of the bracket. In comparison, the minimum factor of safety met design requirements at 1. The mass was lessened to 0.348 kg, representing a 49.2% decrease in comparison with pre-optimization levels. The 3D-printed bracket was fabricated by employing a 3D printer, thereby achieving the aforementioned mass abatement. The battery pack parts exhibited a bright surface with low roughness and no discernible warping or deformation defects. As revealed by the assembly results, the components of the battery pack bracket are tightly coordinated with each other, with no evident assembly conflicts, revealing that the dimensional accuracy and fit of the completed parts meet production requirements. These findings lay solid groundwork for the mass production of high-performance battery pack brackets.

Simulation of non-resonant high-order harmonics energetic particle modes in tokamak plasmas

Based on the parameters of the HL-2A experiment, the effect of energetic particles (EPs) on non-resonant high-order harmonics energetic particle modes (EPMs) with q min>1 is investigated in the present work. Hybrid kinetic-magnetohydrodynamic nonlinear code M3D-K is performed to simulate the linear properties and the nonlinear evolution of the non-resonant EPM during neutral beam injection (NBI). To deeply understand the physical mechanism of interaction resonant between energetic-ions and non-resonant EPM, this work compares the effects of passing energetic particles and trapped energetic particles on the non-resonant EPM instabilities. It is numerically identified that EPs’ effects on high n harmonics (m/n = 2/2, 3/3, 4/4) instability are more obvious than the m/n = 1/1 mode. Furthermore, the effects of energetic particles injection energy, the minimum safety factor q min , toroidal rotation and beam ion distribution on the features of high n harmonics are also investigated specifically. Toroidal rotation is found to suppress high n harmonics, which is more obvious for the modes driven by trapped particles. Nonlinear simulation results show that these non-resonant high n harmonics can induce larger energetic ion transport, which may affect the plasma confinement performance.

Enhancing stability analysis of open-pit slopes via integrated 3D numerical modeling and data monitoring

The slope at Zhahanur open-pit mine (China) has experienced significant and prolonged deformation, posing a considerable risk to life and property within the mining area. To analyse the deformation and failure mechanism of the rock slope, geotechnical investigations, numerical simulations, and long-term movement monitoring were undertaken. In order to improve the efficiency of slope pretreatment, a point elimination method was proposed for the slope surface, and a 3D geological model of mining area was established. A systematic analysis was performed on monitoring data from surface slope radar and underground inclinometers, enabling the identification of the potential sliding surface and deformation pattern of northern slope in a rational manner. Additionally, through three-dimensional numerical simulation, the feasibility of the mining scheme that incorporates waste dump inside the pit was explored. These simulations accurately captured the varying deformation patterns at different levels and exhibited good agreement with available field monitoring data. The findings revealed a composite multi-stage slope failure pattern primarily controlled by weak layers. The safety factors associated to two competing slip surfaces were determined to be 1.20 and 1.15, respectively. To ensure the safe extraction of coal resources from the deformed slope, a combined mining scheme of in-pit dumping and mining is proposed in the study. The proposed scheme was shown to meet the production needs, with a minimum safety factor of 1.08 for rock slope under the mining scheme. By integrating various field monitoring techniques with numerical simulations, a collaborative monitoring scheme was devised to effectively and promptly identify potential sliding surface and implement necessary mining and control measures to ensure slope stability. This comprehensive approach provides valuable insights into the deformation behavior of the rock slope and facilitates the implementation of proactive measures to mitigate risks associated with slope instability.

Failure characteristics and seismic behavior of steel basalt hybrid fiber reinforced concrete lining for the tunnel in strong earthquake areas

The effect of a high-intensity earthquake on a tunnel can be catastrophic. To minimize the damage of the earthquake to the tunnel, the mechanical properties of tunnel lining need to be improved in strong earthquake areas. Thereby, this paper proposes a steel basalt hybrid fiber reinforced concrete (SBHFRC) as an alternative construction material for the lining. Then, the failure characteristics and seismic performance of SBHFRC are studied and compared with that of plain concrete (PC) and steel fiber reinforced concrete (SFRC). The results show that the toughness of SFRC is better than that of SBHFRC. Furthermore, the initial crack load and failure load of SBHFRC lining are significantly higher than that of PC lining. The numbers of cracks observed in the SBHFRC lining and SFRC lining are more than that in the PC lining. But the distribution of cracks in SBHFRC lining is relatively uniform. The bearing capacity of SFRC lining and SBHFRC lining is basically the same, although significantly higher than that of PC lining. The seismic performance of different fiber concrete linings is further explored through numerical simulation. Under strong earthquakes, the damage areas of the lining are mainly concentrated at the tunnel vault bottom and vault near the fault, and the SBHFRC damage degree and range are the smallest. Compared with PC lining, the minimum safety factors of SFRC lining and SBHFRC lining are increased by 7.5 times and 11.2 times, respectively, which shows that SBHFRC lining has good seismic performance.

Analisis Stabilitas Tempat Pembuangan Akhir (TPA) Sampah Akibat Pengaruh Perubahan Sifat Mekanis Material Sampah

The stability of landfill is a crucial aspect of waste management. Numerous factors influence the stability of landfill, one of which is the alteration of the mechanical properties of the waste material. This research aims to analyze landfill stability by considering the effects of changes in the mechanical properties of waste material. A construction stage analysis was conducted to model the process of altering the mechanical properties of waste material. The analysis was divided into 13 stages corresponding to the number of landfill steps. The initial five stages were modeled as waste with an age of < 5 years, stages 6-10 were modeled as waste with an age of 5-10 years, and the last three stages were modeled as waste with an age of > 10 years. Stability analysis using the finite element method was conducted using the concept of shear strength reduction. The analysis results indicated changes in the landfill's safety factor throughout its operational period. Stages 1-5 experienced changes in the safety factor, although these changes were not significant. Stages 6-10 witnessed a considerable decrease in the safety factor before experiencing an increase in stage 11, followed by a continuous decline until the end of stage 13. Despite changes in the safety factor during the operational process, the overall safety factor values obtained still met the minimum safety factor criteria required.

Optimizing the Design Structure of Recycled Aluminum Pressing Machine using the Finite Element Method

Optimizing the Design Structure of Recycled Aluminum Pressing Machine using the Finite Element Method

A novel stability equation for the estimation of the factor of safety for homogeneous dry finite slopes

AbstractThis paper introduces a novel closed‐form equation (surrogate model) for approximating the Morgenstern–Price estimate of the factor of safety of homogeneous dry finite slopes with circular failure surfaces. Unlike typically used methods, the proposed equation does not require the definition of a critical failure surface, splitting the soil mass into slices, or the iterative reduction of soil resistance to the limit state. It can be easily programmed into calculators or computers and accurately determines the minimum factor of safety based on the shear strength parameters and slope geometry—meaning that it is ideally suited for integration into reliability calculations. The equation is determined parametrically for various soil parameters and slope geometry using the Morgenstern–Price method and compares favorably with conventional techniques, such as slope stability charts, limit equilibrium, and strength reduction methods (SRM). From a practical perspective, the proposed equation greatly simplifies the analysis of the slope stability as the creation of a numerical model is not required and is suited to use in the feasibility stage of a project, for example, for large linear infrastructure projects with differing slope geometries or in situations where a quick assessment is desired.

Isotope impact on Alfvén eigenmodes and fast ion transport in DIII-D

Measurements of beam driven Alfvén Eigenmode (AE) activity in matched deuterium (D) and hydrogen (H) DIII-D plasmas show a dramatic difference in unstable mode activity and fast ion transport for a given injected beam power. The dependence of the unstable AE spectrum in reversed magnetic shear plasmas on beam and thermal species is investigated in the current ramp by varying beam power in a sequence of discharges for fixed thermal and beam species at fixed density. In general, a spectrum of Reversed Shear Alfvén Eigenmodes (RSAEs) and Toroidal Alfvén Eigenmodes (TAEs) are driven unstable with sub-Alfvénic D beam injection while primarily only RSAEs are driven unstable for the H beam cases investigated. Further, for a given beam power, the driven AE amplitude is always reduced with H beams relative to D and for H thermal plasma relative to pure D or mixed D/H plasmas. Estimates of the fast ion stored energy combined with modeling using the hybrid kinetic-MHD code MEGA indicate that the dominant mechanism contributing to the difference between H and D beam drive is the faster classical slowing down of H beam ions relative to D and the resultant lower beam ion pressure. Calculations of the AE induced stored energy deficits using the reduced critical gradient model TGLFEP show quantitative agreement with the observed dependencies on injected power, isotope and minimum safety factor.

NGHIÊN CỨU TRƯỜNG ỨNG SUẤT BÁNH CÔNG TÁC TẦNG ĐẦU TIÊN MÁY NÉN ĐỘNG CƠ TUA BIN KHÍ TV3-117 BẰNG MÔ PHỎNG SỐ

This article presents the results of stress field calculations for the first stage compressor impeller using the one-way fluid-structure interaction (FSI) method, which helps determine stress concentration zones and safety factors. Numerical analysis conducted with Ansys software reveals that stress concentration occurs near the blade root on the suction side and within the blade lock-disc zone. In these stress concentration zones, such as the blade lock-disc zone and blade suction side, the minimum safety factor is found to be above 2.27. These findings serve as a foundation for future research on impeller stress fields using two-way FSI methods and for providing recommendations to optimize the stress concentration field in the compressor disc.