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This paper coupled a water-air two-phase hydrodynamic (WATPH) model with the Iverson's method to analyze the influence of the Lisse effect on the fast groundwater pressure (Pw) response and the slope stability. Furthermore, the sensitivities of the driving force and loess soil parameters were investigated. Results showed that the WATPH model simulated the height and rise of the depth to the water table reasonably well. The depth to water table before rainfall (H0) had a significant impact on the Lisse effect and the slope stability. When the H0 was less than approximately 1 m, the rainfall triggered a significant Lisse effect and decreased the slope factor of safety (Fs). When the rainfall intensity (Ri) was higher than the saturated hydraulic conductivity (Ks), the Lisse effect and the Fs slightly changed with the increase of the Ri, and the slope tended to be unstable with continuous rainfall. With increasing Ks, the Lisse effect noticeably increased, and the minimum Fs quickly decreases. The analysis of the normalized sensitivity coefficient revealed that H0 had a dramatic impact on the Lisse effect and loess slope stability. The different Ri and Ks values had prominent influences on the Lisse effect and slight impacts on Fs. [ABSTRACT FROM AUTHOR]

The stability analysis of the backfill support system has been a significant analysis of stope performance in stoping mining method. For the past decades, the strength of exposed backfill was preferred to be conducted using analytical solutions based on the limit equilibrium theory. Nevertheless, these solutions have neglected the effect of layering that is endured by the backfill in the large stope. These methods appear to provide unrealistic results in stratified backfill stopes. This study introduces a modified solution that considers the shearing force along the backfill layers interface. The proposed solution method confirms that when the effect of layering is included the solution differs from the existing limit equilibrium solutions. Various examples are provided to validate the proposed analytical solution method. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anti-sliding stability safety is a critical issue that must be given sufficient and widespread attention during the entire lifecycle of gravity dams. The calculated anti-sliding stability safety factor (ASS-SF) is usually compared with the allowable value required by the standards in the traditional method, which ignores the influence of material parameter uncertainties and leads to unreasonable safety evaluation results. Therefore, the nonlinear functional relationship between the stability safety factor (SF) and the random variable parameters is constructed based on the response surface equations, and the distribution types of SF sequences calculated by the Monte Carlo sampling are determined, then a probabilistic stability evaluation method for concrete gravity dams is proposed. Engineering application shows that the calculated SF obeys the normal distribution; the minimum guaranteed rate of different sliding paths in a gravity dam is 86.66%, and the guaranteed rate for the overload safety factor (OSF) is 36.00%. The results imply that a guaranteed rate for the allowable value of the ASS-SF should be provided when making the stability safety evaluation of the dams, especially the OSF. The outcome of this research will advance the understanding of stability evaluation of concrete dams, and reduce the potential risk of sliding instability of concrete dams. [ABSTRACT FROM AUTHOR]

Fibre-reinforced polymer (FRP) reinforcement has been employed as an alternative to conventional steel reinforcement in concrete structures, which is attributed to its excellent strength and corrosion resistance. However, one drawback is that FRP reinforcements are brittle and affect the ductility of concrete structures. One of the recent effective techniques proposed to overcome ductility issues is the compression yielding (CY) concept. The CY mechanism allows the structure to fail differently than the conventional FRP-reinforced concrete structure. Thus, the existing design recommendations as per the current codes for FRP-reinforced concrete structures are not appropriate. Hence, reliability studies are crucial for the development of a functional CY beam design in order to emphasise the structure's lifetime performance and to guarantee safety requirements. In this study, a reliability-based design approach is developed for a compression-yielded FRP-reinforced concrete beam (CY beam) using load and resistance factor design (LRFD). Firstly, the flexural failure modes of CY beams are discussed. The uncertainties involved in the development of the probabilistic model for the CY beam are defined. A case study is consequently conducted for a CY beam with random variables that are associated with the statistical characteristics of material properties and load. The reliability analysis method employed in this research is the Hasofer–Lind method. The results suggest the importance of choosing appropriate design variables and stochastic parameters for CY blocks that contribute to a higher level of reliability. The reliability index and resistance factors of a CY beam are then evaluated using the Monte Carlo Simulation computational method. The reliability index value of 3.336 is obtained from the simulation, which indicates that the CY beam demonstrates ductile behaviour. The results not only demonstrate ductile behaviour but also contribute to a possible reduction in material costs and a substantial safety margin. When compared to conventional FRP-reinforced concrete beams, for different load ratios, CY beams showed higher resistance and better reliability levels. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Slope stability is a major safety concern of rockfill embankments. Since rockfills are incohesive materials, only friction angle is considered as a shear strength parameter in the slope stability analysis of rockfill embankments. Recently, it was found that confining pressure can significantly affect the mean value and variance of the friction angle of rockfills. Since the confining pressure spatially varies within a rockfill embankment, the effect of stress-dependent spatial variability in the friction angle of rockfills should be investigated for slope stability evaluation of rockfill embankments. In the framework of the Limit Equilibrium Method (LEM), an approach is proposed for the slope stability analysis of rockfill embankments considering the stress-dependent spatial variability in the friction angle. The safety factors of slope stability are computed with variable values of the friction angle at the bases of slices which are determined by the stress-dependent mean value and variance of the friction angle of rockfills. The slope stability of a homogeneous rockfill embankment is analyzed to illustrate the proposed approach, and a parametric analysis is carried out to explore the effect of variation in the parameters of the variance function of friction angle on slope stability. The illustrative example demonstrates that the stress-dependent spatial variability of friction angle along the slip surface is obvious and is affected by the location of the slip surface and the loading condition. The effects of the stress-dependent spatial variability of the friction angle on the slope stability of high rockfill embankments should be considered. [ABSTRACT FROM AUTHOR]

In general, the design of a safe and rational laneway support scheme signifies a crucial prerequisite for ensuring the security and efficiency of mining exploitation in mines. Nevertheless, the conventional empirical support system for mining laneways faces challenges in assessing the rationality of support methods, which can compromise the safety and reliability of the laneways. To address this issue, the safety factor was incorporated into research on laneway support, and a safety evaluation method for laneway support in line with the safety factor was established. In light of the data from a specific iron mine laneway in central China, the CRITIC method was employed to preprocess the sample data. Going one step further, a Bayesian algorithm was utilized to optimize the hyperparameters of the CatBoost model, followed by proposing a prediction model based on the BO-CatBoost model for evaluating laneway safety factors of plain shotcrete support. Furthermore, the performance indexes, such as the root mean square error (RMSE), the mean absolute error (MAE), the correlation coefficient (R2), the variance accounts for (VAF), and the a-20 index, were determined to examine the predictive performance of each proposed model. In contrast to the other models, the BO-CatBoost model demonstrated the optimal predictive output item for safety factors with the lowest RMSE and MAE, the largest R2 and VAF, and an appropriate a-20 index value of 0.5688, 0.4074, 0.9553, 95.25%, and 0.9167 in the test set, respectively. Therefore, the BO-CatBoost model was proven to be the most appropriate machine learning method that can more accurately predict the safety factor, which will provide a novel approach for optimizing laneway support design and laneway safety evaluation. [ABSTRACT FROM AUTHOR]

This study takes the mine wall of the isolated mine pillar in the Dongguashan Copper Mine as the research object. Based on the mechanical model of the mine wall under the trapezoidal loading of the backfill, the expressions for calculating the safety factor of the mine wall were derived by considering the load-bearing conditions of the backfill–mine-wall system under different roof-contacted filling rates. On this basis, the variation law of the safety factor of the mine wall with the roof-contacted filling rate was obtained, and the calculation result was verified by a numerical simulation and a field test. The research shows that for the same mine wall width, when the roof-contacted filling rate exceeds 9.53%, the safety factor of the mine wall exhibits a "trapezoidal" variation pattern with the increase in the roof-contacted filling rate. Moreover, the comprehensive benefits of isolated pillar recovery are made more credible by maintaining a wall width of 3 m and a filler jointing rate between 30% and 74.49%. This study analyzes the effect of the roof-contacted filling rate on the stability of the mine wall, which can provide a theoretical basis for mining isolated pillars by the filler method in deep mines. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

There has been limited research conducted to date on the role and significance of soil parameters in an unsaturated state on the amount of deformation and safety of reinforced deep urban excavations. This study investigates stress–deformations and static/pseudostatic safety factors against the general failure of an anchored deep excavated wall in an unsaturated soil deposit through two-dimensional finite-element modeling and limit equilibrium analysis, respectively. A suction-dependent elastic–plastic Mohr-Coulomb model is used in the analyses considering the effective stress approach in unsaturated soils. The results obtained from numerical modeling are validated against field monitoring data, including wall deformations and tensile forces in the anchors. A series of parametric studies are then performed assuming different groundwater levels, surcharge loads, and surcharge load distances from the wall crest to investigate their effects on the stability and deformation of the unsaturated soil excavation. Results are compared with those obtained from the corresponding routine analyses, in which the unsaturated state of the soil is not considered. The parametric study shows that the depth of the groundwater table is more influential on the results compared with the intensity and location of the surcharge load. The study demonstrates that unsaturated soil conditions result in a reduction of up to 37% in the maximum horizontal deformations of the excavation and increase the static and pseudostatic safety factors against general failure by 28% and 19%, respectively. In addition, taking unsaturated soil conditions into account during analysis leads to a decrease of up to 31% in the estimated tensile forces in the anchors. More importantly, it is shown that a more cost-effective stabilization plan can be developed for deep urban excavations by considering soil unsaturation effects, as demonstrated by comparing the results of the numerical analyses with the field data. Practical Applications: Presenting a safe and economically feasible plan for stabilizing deep urban excavations is a significant challenge for geotechnical engineers. Traditionally, engineers have relied on classical methods that consider soil parameters under dry or saturated conditions. However, in practice, the soil above the water table is unsaturated, and its mechanical properties are greatly influenced by the saturation level. Contrary to common belief, rainfall or pipe leakage near an excavation site does not fully saturate the soil and eliminate suction effects. Previous studies have shown that percolation from rainfall or other factors does not completely infiltrate clay-rich soils, mainly affecting moisture content and suction at shallow depths. This study evaluates the stress–strain behavior and the factor of safety against sliding in a deep excavated wall in Tehran, Iran, by considering unsaturated soil parameters. Comparing the outcomes with conventional methodologies, the results demonstrate that incorporating unsaturated soil parameters provides more accurate results aligned with field observations. This approach also results in smaller displacements of the excavation wall and higher safety factors against wall sliding. Accordingly, incorporating unsaturated soil parameters ensures accurate safety assessments for urban excavation walls and enables the creation of cost-effective and optimized design suggestions. [ABSTRACT FROM AUTHOR]

On September 28, 2018, a 7.5-magnitude earthquake struck Palu City, Sigi Regency, and Donggala Regency in Central Sulawesi. It triggered liquefaction in different locations, including Balaroa, Petobo, Jono Oge, and Sibalaya; Typically, a significant number of studies conducted in the Balaroa region relied on a small amount of field test data to cover a rather large area. This research aims to map the liquefaction vulnerability by analyzing the data from both the Swedish Weight Sounding (SWS) and the Standard Penetration Test (SPT) in the Balaroa area. The SWS data was acquired through mapping using a systematic grid sampling method at ten different locations. The liquefaction potential was analyzed based on the N values by converting the SWS data (Nsw and Wsw) to N values using the Inada equation (1960). Afterward, the analysis findings were verified by comparing them with the SPT data obtained from the same area. Based on the SWS and SPT data analysis results, all locations, including the adjacent areas, exhibited very high liquefaction vulnerability. In contrast, the SPT data indicated that the areas further from the spots exhibited low and very low liquefaction. The findings indicated that the occurrence of post-earthquake liquefaction in Balaroa and other regions within Palu City is prone to recurrence following earthquakes of specific magnitudes. [ABSTRACT FROM AUTHOR]

The article presents substantiation of the possibility to extend the operation of the SGT5-2000E series gas turbine units beyond the period specified by the manufacturer after which the "hot" parts and, primarily, the cooled nozzle vanes and rotor blades of the turbine's first stages should be replaced. Each gas turbine unit is provided, along with the operation manual, with a maintenance program proceeding from the assigned fleet service life, in accordance with which the time of operation with one set of cooled blades of the turbine's first stages is determined. A gas turbine cannot operate reliably unless its worn "hot parts" are checked and, if necessary, are subjected to restorative repair. As a rule, this can be done in the course of appropriately long outages (e.g., minor inspections, overhauls, and hot gas path visual examinations). All time-dependent wear coefficients are calculated simultaneously, and the calculation result is expressed in equivalent hours of operation (equiv. h), which vary depending on the pattern and number of working cycles, operational mode, used fuel, and water injection availability. A service life reduction is determined and expressed as an equivalent number of operation at the base load. The total number of equivalent hours of operation is the sum of hours calculated under the specific operation conditions. The article presents scientifically substantiated recommendations for a limited extension of the interval between maintenances obtained from mathematical modeling of the wear processes of cooled nozzle vanes and rotor blades in the first stages, and from an analysis of a change in the longevity characteristics of the alloy they are made of. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to natural sedimentation and artificial filling, slopes exhibit heterogeneity in the form of multi-layer soils, namely, layered slopes. Compared with homogenous slopes, the failure mechanism of layered slopes is more complex owing to the different shear strengths of each soil layer. Therefore, it is of great importance to gain insight into the stability of layered slopes. In this study, the upper bound theorem of limit analysis incorporated with a pseudo-static approach is utilized to investigate the seismic stability of two kinds of two-layered slopes: one with a stiff lower soil layer and the other with a weak lower soil layer. Three failure patterns, namely face failure, toe failure and base failure, are taken into account. A depth coefficient (Δ) is introduced to describe the distribution of two soil layers. The layer-wise summation method is adopted to calculate the safety factor and yield acceleration coefficient more conveniently. Based on Newmark's method, the earthquake-induced horizontal displacement is estimated. The calculated results are validated by comparisons with published literature and the numerical method in terms of safety factor, critical failure surface and yield acceleration coefficient. The results show that the depth coefficient has a significant influence on the failure mechanism of two-layered slopes by determining whether the stability of upper-layered soil is dominant in the overall slope stability or not. Inaccurately identifying the failure patterns will overestimate the seismic performance of two-layered slopes in the aspects of safety factor and yield acceleration coefficient, leading to an underestimation of earthquake-induced horizontal displacement. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Toll roads are infrastructure built to improve the regional and national economy. The challenge faced on this toll road is soft soil as deep as 7 m. This research analyzes the stability of the embankment with a slope of 1V:2H and a height of 4.5 m without and with repair using the Limit Equilibrium Method (LEM) because the Safety Factor (SF) value in LEM provides a more critical value than the Finite Element Method (FEM). In addition, the settlement amount was also analyzed. The SF value in short term conditions with an embankment load of 1.31 < 1.4 and earthquake load of 0.83 < 1.1. Then, at pavement installation, 1.33 < 1.4, plus earthquake load 0.84 < 1.1. In long term conditions, during the operational period, 1.48 < 1.5, plus earthquake load 0.84 < 1.1. This indicates that the soil requires improvement. To address the problem, soil improvement utilized 2.5 m deep soil replacement and 75 kN woven geotextile. The SF value with repair under short term conditions, with embankment load 1.53 > 1.4, plus earthquake load 1.18 > 1.1. Then, at the time of pavement installation, 1.56 > 1.5, plus earthquake load 1.19 > 1.1. In the long term condition, it was 1.62 > 1.5 at the time of operation, plus earthquake load 1.22 > 1.1. The total settlement after the operation is 0.21 cm ≤ 10 cm and the settlement rate is 0.68 < 2 cm/year. This shows that improvements can increase the SF value and reduce settlement.

Abstract Bodovalle is a siderite mine located in northern Spain that is currently in the closure phase. The mine was exploited using the room-and-pillar method. Subsidence processes have occurred previously and reached the surface because of the collapse of several pillars into the mine. To prevent such risky situations, the closure plan has been modified and the backfilling of some rooms has been considered. This study aimed to evaluate the global stability of room #1.1 after backfilling. This paper combines the use of traditional techniques, numerical modelling and remote sensing to achieve this objective. Limit equilibrium methods, LIDAR technology and numerical methods-based software were employed to evaluate the stability of rooms and pillars surrounding room #1.1 and considering different backfilling levels. In all possible backfilling scenarios involving room #1.1, the impact on the surface and neighboring rooms is negligible. In addition, no substantial changes in the safety factors and deformations of the neighboring rooms were observed for both studied levels of backfilling. Thus, backfilling is an adequate countermeasure to avoid subsidence.

Understanding the primary and secondary relations of influencing factors is crucial for predicting deformation and controlling collapse in cutting slopes. Using a cutting slope along the Shuangcheng to Dalijia expressway in Gansu Province as the research object, this research utilized the FLAC3D finite element software platform to establish dynamic correlations between saturation, gravity, and soil shear strength through FISH language. Based on this, safety factors of the cutting slope were calculated under different rainfall intensities, slope ratios, and rainfall duration. Grey relational theory was applied to determine the primary and secondary relationships of key factors affecting shallow collapse of cutting slopes under rainfall conditions. Indoor rainfall experiments and on-site ecological protection tests were conducted to summarize the shallow collapse mechanism and propose the environmental control measures. The study revealed that the failure mode of cutting slopes transitioned from deep overall sliding to shallow local sliding during rainfall. As the slope ratio decreased, the shallow collapse area gradually shifted from the slope shoulder to the foot of the cutting slope. Cumulative erosion rates of shallow soil in cutting slopes decreased initially and then increased over time during rainfall. Installing arch skeletons and reducing the slope ratio enhanced the cutting slope's resistance against shallow collapses. Among with the protective materials, polypropylene fiber-reinforced soil protective materials exhibited the best timeliness and ecological control effect for shallow collapses of cutting slopes compared to HP-FGM and EFM materials.

The article presents the stability analysis of two adjacent waste landfills located in a potentially unstable territory. One of the waste landfills is reclaimed and consists of ash. Municipal solid waste is actively deposited in the second landfill. In the space between the landfills, the expansion of the municipal solid waste landfill is planned, with a partial overlap of the reclaimed ash landfill. The instability of the area where the landfills are located is due to its susceptibility to the formation of landslides. The article presents the results of experimental verifications of the peak shear strength parameters of the ashes and the peak and residual shear strength of the soils forming the subsoil of both landfills and serve as input for stability analyses. The shear strength parameters of municipal waste are defined on the basis of literature research. The potential instability of both waste landfill territories was taken into account using the parameters of the residual shear strength of the subsoil. The stability analysis of waste landfills is expressed using both the peak and residual shear strength parameters of the subsoil of waste landfills. In addition, the effect of seismic loading on both landfills is considered in the stability analysis.

Objective Rainfall disasters are one of the most common disasters on loess slopes in northern Shaanxi, and revealing the effects of rainfall on loess slope stability is beneficial for preventing and controlling such disasters. Methods This research studied the mechanical properties of Q2 loess in northern Shaanxi under rainfall conditions through a series of tests. Combined with numerical simulation technology, the influence of these changes on the stability of loess slopes in northern Shaanxi was analyzed.Firstly, the drying-wetting cycles test (cyclic path and the number of cycles) was designed to simulate rainfall conditions (such as intensity, frequency, etc.).Secondly, a triaxial shear test was performed to obtain the variation law of the mechanical properties of the Q2 loess in northern Shaanxi.Finally, taking a loess slope in northern Shaanxi region as an example, finite element calculations were carried out, by which the change characteristics of the slope safety coefficients and plasticity zones under different rainfall conditions were analyzed. Results The results show that (1) the shear strength of Q2 loess after the action of drying-wetting cycles has nonlinear deterioration characteristics. When the number of drying-wetting cycles exceeds a specific range, the marginal effect of the deterioration of the physical and mechanical property parameters of loess is weakened and tends to stabilize. (2) The stability of loess slopes decreases under the effect of rainfall, and it decreases with the increase of rainfall frequency or intensity. (3) The plastic zone of Q2 loess slopes in northern Shaanxi increases with the continuous deterioration of the mechanical properties of the Q2 loess, which reveals a nonlinear characteristic of the influence of rainfall on the stability of the loess slopes. Conclusion The research results can provide a reference for preventing rainfall-induced landslide.

Empirical data relating body mass to immune defence against infections remain limited. Although the metabolic theory of ecology predicts that larger organisms would have weaker immune responses, recent studies have suggested that the opposite may be true. These discoveries have led to the safety factor hypothesis, which proposes that larger organisms have evolved stronger immune defences because they carry greater risks of exposure to pathogens and parasites. In this study, we simulated sepsis by exposing blood from nine primate species to a bacterial lipopolysaccharide (LPS), measured the relative expression of immune and other genes using RNAseq, and fitted phylogenetic models to determine how gene expression was related to body mass. In contrast to non-immune-annotated genes, we discovered hypermetric scaling in the LPS-induced expression of innate immune genes, such that large primates had a disproportionately greater increase in gene expression of immune genes compared to small primates. Hypermetric immune gene expression appears to support the safety factor hypothesis, though this pattern may represent a balanced evolutionary mechanism to compensate for lower per-transcript immunological effectiveness. This study contributes to the growing body of immune allometry research, highlighting its importance in understanding the complex interplay between body size and immunity over evolutionary timescales. [ABSTRACT FROM AUTHOR]

This study of the strength and deformation of coal samples was triggered by the need to define the stress–strain characteristics of pillars during room and pillar mining in the shaft protective pillar at the ČSM Mine. It was probably the world's deepest deployment of this mining method in a coal mine. In order to solve the bearing capacity of pillars, the dependence of coal strength on the slenderness ratio is used. For this reason, coal samples with different slenderness ratios were investigated. After considering the purpose of this research, slenderness ratios (width/height) of 1 to 7.7 were chosen. At the same time, the modulus of deformation as a function of the slenderness ratio was determined, and the vertical deformation of the pillars and the safety factor were calculated. Attention is also paid to the influence of sampling on the results of measured coal strengths. [ABSTRACT FROM AUTHOR]

Glass-metal hetero-bonding through optical epoxy adhesive is frequently used in opto-mechanics and requires high stability. However, the bonding stability is difficult to achieve and predict in massive use cases, where dozens to thousands of metal pads are bonded to mount large optics. Here a universal adhesive bonding technology was proposed and evaluated through reliability analyses based on a limited number of sample tests. Specimens were prepared and tested via standard procedures and equipment; afterward, the lower strength limits were calculated with high reliability. Nominal tensile (6.7 MPa) and shear (4.3 MPa) strength limits at 99.95% reliability were expected for ongoing 30 m aperture telescopes. This study may improve the quality of opto-mechanical interfaces and reduce the risk on constructing extremely large telescopes. [ABSTRACT FROM AUTHOR]

The spherical tokamak (ST) operates in a steady state with a high fusion gain. The 0-dimensional power balance model, including radiation losses to determine Q value as an inductive fusion gain, and the current balance model for determining Q CD as a non-inductive fusion gain, is used to investigate the viability of D– 3 He fuel for a steady-state operation. The spherical tokamak’s geometry, including the magnetic field B t and β th as a ratio of its kinetic pressure to the magnetic pressure, is used to analyse the impact of the confinement enhancement factor H y 2 and the impurity density fraction f I on Q CD . By comparing the obtained values with the device data, plasma characteristics, such as the safety factor q I and Greenwald density limit N G are examined to determine the optimum density limit and safety factor for an assurance about Q ≈ Q CD as the aim of steady-state operation. A comparison with ARIES-III performance is also made. The overall plant power balance equation is included. Furthermore, the desirable plant thermal efficiency value η th and normalised beta value β N for producing net electric power P NET > 1 GW for the ST are achieved. Therefore, ST’s capability of having a lower aspect ratio A and higher elongation κ s than ARIES-III in generating more significant fusion power with lower H y 2 and higher energy confinement time τ E is approved. [ABSTRACT FROM AUTHOR]

This article describes an extensive investigation of the failure mechanisms of a large geotextile mat cofferdam over a deep soft clay layer, where the large geotextile mat was filled with sand. Finite element (FE) analysis was conducted to provide insight into the behaviour of large geotextile mats. The FE results were validated against 1 g model test data and centrifuge test data prior to undertaking a detailed parametric study. It is found that large geotextile mat cofferdam over deep soft clay has two distinctive types of failure mechanisms – global and local failure mechanisms. The global failure mechanism showed the whole dam sank downwards together, and the local failure mechanism included a central standing ridge with two dam sides sliding downwards. A formula, based on the results of the parametric study, was proposed to distinguish the potential failure mechanism of the dam and the foundation soil. For these two different failure mechanisms, both limiting fill height and safety factor of the dam could be predicted using the equations obtained from this study. Finally, a design framework was proposed to provide guidance for designing the large geotextile mat cofferdam over deep soft clay under construction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding the primary and secondary relations of influencing factors is crucial for predicting deformation and controlling collapse in cutting slopes. Using a cutting slope along the Shuangcheng to Dalijia expressway in Gansu Province as the research object, this research utilized the FLAC3D finite element software platform to establish dynamic correlations between saturation, gravity, and soil shear strength through FISH language. Based on this, safety factors of the cutting slope were calculated under different rainfall intensities, slope ratios, and rainfall duration. Grey relational theory was applied to determine the primary and secondary relationships of key factors affecting shallow collapse of cutting slopes under rainfall conditions. Indoor rainfall experiments and on-site ecological protection tests were conducted to summarize the shallow collapse mechanism and propose the environmental control measures. The study revealed that the failure mode of cutting slopes transitioned from deep overall sliding to shallow local sliding during rainfall. As the slope ratio decreased, the shallow collapse area gradually shifted from the slope shoulder to the foot of the cutting slope. Cumulative erosion rates of shallow soil in cutting slopes decreased initially and then increased over time during rainfall. Installing arch skeletons and reducing the slope ratio enhanced the cutting slope's resistance against shallow collapses. Among with the protective materials, polypropylene fiber-reinforced soil protective materials exhibited the best timeliness and ecological control effect for shallow collapses of cutting slopes compared to HP-FGM and EFM materials. [ABSTRACT FROM AUTHOR]

Rapid sedimentation is widely recognized as a crucial factor in initiating the instability of submarine slopes. Once the slope fails, the subsequent landslide poses a significant threat to the safety of underwater infrastructures and potentially leads to severe damage to seabed pipelines, offshore foundations, and oil and gas exploitation wells. However, there is currently a lack of numerical methods to effectively assess the real-time stability of submarine slopes under rapid sedimentation. This study firstly employs a calibrated finite element (FE) model-change approach to reproduce the rapid sedimentation processes and proposes a concise method to calculate the safety factors for the real-time stability of sedimenting submarine slopes. Further, a parametric analysis is carried out to evaluate the effect of varying sedimentation rates on slope stability, and the critical sedimentation rate is numerically solved. Moreover, the effect of seismic events with different occurring times on the stability of rapidly sedimenting slopes is investigated in depth, and the most critical seismic loading pattern among various acceleration combinations is achieved. The results indicate that the presence of weak layers during sedimentation is a critical factor contributing to slope instability. The introduced rate of decrease in the safety factor proves valuable in assessing slope safety over a specific period. As the occurrence time of seismic events is delayed, the seismic resistance of the slope decreases, increasing the likelihood of shallower sliding surfaces. The findings offer insights into the mechanisms by which rapid sedimentation influences the stability of submarine slopes and provide valuable insights for predicting the potential instability of rapidly sedimenting slopes under specific seismic activity levels. [ABSTRACT FROM AUTHOR]

Wave-induced seabed liquefaction significantly jeopardizes the stability of marine structures and the safety of human life. Susceptibility assessment is key to enabling spatial predictions and establishing a solid foundation for effective risk analysis and management. However, the current research encounters various challenges, involving an incomplete evaluation system, poor applicability of methods, and insufficient databases. These issues collectively hinder the accuracy of susceptibility assessments, undermining their utility in engineering projects. To address these challenges, a susceptibility assessment method with the safety factor was developed as the key assessment parameter, allowing for a comprehensive susceptibility assessment across the silt-dominated nearshore environment using Empirical Bayesian Kriging (EBK). The safety factor is determined by combining the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR), which characterize wave loadings and sediment properties in the study area, respectively. This method was applied in the Chengdao region of the Yellow River Estuary, China, a typical silt-dominated nearshore environment where wave-induced liquefaction events have been reported as being responsible for multiple oil platform and pipeline accidents. By collecting the regional wave and seabed sediment data from cores spanning from 1998 to 2017, the safety factors were calculated, and a zonal map depicting the susceptibility assessment of wave-induced seabed liquefaction was created. This study can serve as a valuable reference for the construction and maintenance of marine engineering in liquefaction-prone areas. [ABSTRACT FROM AUTHOR]

Currently, Indonesia has entered a new phase in the development of modern transportation infrastructure, namely high-speed trains initiated by PT Kereta Cepat Indonesia China. The design of the facility operated is an Electrical Multiple Unit (EMU) CR400AF that can drive up to speeds of 350 km / h. Of course, high train speed requires the reliability of railway road infrastructure, including the geometry and components of rail roads. The technical specifications of high-speed rail roads have been regulated in the Minister of Transportation Regulation Number 7 of 2022. The type of rail used by high-speed railway line components with a rail road width of 1435 mm is type R60 rail. However, the determination of the type of high-speed railway in Indonesia has not been completed by analyzing the strength of the rail structure in bearing the load working on it. Thus, this study discusses the influence of rail road geometry on the speed of facilities and evaluates the strength of Type R60 rail structures in receiving high-speed train loads. The analysis method uses the Beam on Elastic Foundation (BOEF) method which assumes the behavior of rails as continuous beams that receive loads on elastic foundation pedestals. The results of the study found that the value of the realized radius and minimum radius of the horizontal arch respectively amounted to 9,500 m and 8,502.94 m greater than the horizontal arch permit radius of 7,000 m, while for the value of the permit radius and vertical radius of the vertical arch of 25,000 m. So that the optimization of the horizontal curved radius to 8,502.94 m to be more in line with the ability of the path to serve passing facilities and is expected to be more effective and efficient in planning. The static load and dynamic load of the EMU wheel CR400AF of 81,662.50 N and 243,522.90 N. The maximum voltage and rail clearance voltage were obtained at 134.53 N/mm2 and 228.57 N/mm2. The strength of the rails is written in the form of a safety factor (SF) number. The calculation results show that the most critical SF value of the rail in receiving the load of high-speed trains is 1.70. Based on the results of BoEF calculations, R60 type rails have a high safety value in withstanding static loads and dynamic loads of high-speed trains. [ABSTRACT FROM AUTHOR]

Purpose: To investigate safety and performance aspects of parallel‐transmit (pTx) RF control‐modes for a body coil at B0≤3T$$ {B}_0\le 3\mathrm{T} $$. Methods: Electromagnetic simulations of 11 human voxel models in cardiac imaging position were conducted for B0=0.5T$$ {B}_0=0.5\mathrm{T} $$, 1.5T$$ 1.5\mathrm{T} $$ and 3T$$ 3\mathrm{T} $$ and a body coil with a configurable number of transmit channels (1, 2, 4, 8, 16). Three safety modes were considered: the 'SAR‐controlled mode' (SCM), where specific absorption rate (SAR) is limited directly, a 'phase agnostic SAR‐controlled mode' (PASCM), where phase information is neglected, and a 'power‐controlled mode' (PCM), where the voltage amplitude for each channel is limited. For either mode, safety limits were established based on a set of 'anchor' simulations and then evaluated in 'target' simulations on previously unseen models. The comparison allowed to derive safety factors accounting for varying patient anatomies. All control modes were compared in terms of the B1+$$ {B}_1^{+} $$ amplitude and homogeneity they permit under their respective safety requirements. Results: Large safety factors (approximately five) are needed if only one or two anchor models are investigated but they shrink with increasing number of anchors. The achievable B1+$$ {B}_1^{+} $$ is highest for SCM but this advantage is reduced when the safety factor is included. PCM appears to be more robust against variations of subjects. PASCM performance is mostly in between SCM and PCM. Compared to standard circularly polarized (CP) excitation, pTx offers minor B1+$$ {B}_1^{+} $$ improvements if local SAR limits are always enforced. Conclusion: PTx body coils can safely be used at B0≤3T$$ {B}_0\le 3\mathrm{T} $$. Uncertainties in patient anatomy must be accounted for, however, by simulating many models. [ABSTRACT FROM AUTHOR]

Earthquakes impact the stability of municipal solid waste (MSW) landfills, especially those with high water levels, and may further lead to disastrous landslides. Numerical analysis offers an efficient and cost-effective way to study the seismic stability of a landfill. In this study, the finite difference nonlinear analysis method was employed to meticulously evaluate the dynamic response of landfills under varying water levels and seismic intensities. The analysis was guided by the seismic instability and centrifuge test outcomes. The rationality of the computational model was verified by examining the responses of acceleration and pore pressure. Subsequently, the time history curve of the dynamic safety factor was derived from the dynamic response of landfills. The results indicated that a landfill was more susceptible to large earthquake effects, and its stability decreased as the water level rose, with the safety factor decreasing to a critical point under the coupling effect of strong earthquakes and high water levels. In contrast, the stability of the landfill with low water levels was good under weak earthquake conditions, with only a slight decrease in the safety factor observed. The seismic stability of a landfill was significantly influenced by both accumulative deformation and negative excess pore pressure. A certain degree of hysteresis in the landfill's instability was also observed compared to the earthquake loading process. The time history curve of the safety factor can offer a comprehensive insight into seismic stability under diverse conditions. Additionally, future research efforts are needed to better determine the values of strength parameters of MSW in seismic analysis. [ABSTRACT FROM AUTHOR]

In order to analyze the adverse effect of flood affection on slope stability, the analytical expressions of buoyancy force and capillary force, hydrodynamic pressure and impact force, and scour erosion were proposed based on the aging characteristics of soil shear strength and limit equilibrium theory. According to the load combination and flood action, shear failure occurs preferentially at the foot of slope. Then, the plastic zone continues to extend upward to produce traction landslide disaster mode. Furthermore, the power function relation between shear strength index and time was established. The nonlinear accelerated creep model was also obtained. At the same time, the safety factor formula for flood loading effect slope aging stability, the time-varying characteristic value of anchor force and the compensation value of anchor force were also obtained and used to research sliding mechanism. In addition, the numerical calculation example shows that the slope safety factor decreases by more than 20 % considering the effect of flood ascending scour and impact, and the compensation value of anchorage force increases obviously with time increasing. Simultaneously, the change rate of compensation value of anchorage force increases nonlinearly with the increase of design safety factor.

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.

Abstract A huge number of sinkhole events has been recorded in different Italian urban areas, with an occurrence frequency largely increasing in the last decades, sometimes even causing loss of human lives. The main reason for such catastrophic events is the presence of man-made underground cavities, excavated within soft rocks, several decades ago and then abandoned, at shallow depths. Here, the possibility of interaction with overlying buildings and infrastructures and the corresponding sinkhole hazard is relatively high. In such contexts, the low mechanical properties of the soft rock formations where the cavities have been excavated, like those formed of calcarenites, which outcrop in large areas of Southern Italy, and their high susceptibility to weathering processes, represent one of the most important predisposing factors for instability. Therefore, assessing the stability of underground cavities is crucial for land management and planning purposes. The mechanically-based stability charts developed by Perrotti et al. (Int J Geomech 18(7):04018071, 2018) have proved to be a valid tool for preliminary stability assessment and, although allow to identify an eventual proneness of the cave to instability, they do not provide quantitative assessment about the safety margin itself. In that regard, this study intends to present the most recent outcomes obtained in the development of the methodology and is aimed at promoting an enhanced way for their application, so that the charts can become an operative tool for preliminary sinkhole hazard assessment in similar regions in the world.

The coefficient of safety is an important index for the evaluation of slope stability. The safety coefficients calculated based on different instability criteria are significantly different, and the variability of the results will directly affect the evaluation of the stability state of slopes. In this paper, taking the step-type excavated slope of the Wanhuashan Trench Construction Project as the object, FLAC3D finite difference software was used to calculate the safety coefficient of loess slopes based on three different types of instability criteria, namely the calculation non-convergence criterion, the plastic penetration criterion and the displacement abruptness criterion, and to compare and analyze the differences, advantages and disadvantages of the evaluation results of the three criteria. The results of the study shows that there is a certain difference in the magnitude of safety coefficients obtained by using different instability criteria, with the order of magnitude being displacement abrupt change criterion > computational non-convergence criterion > plastic penetration criterion. The computational non-convergence criterion is easy to use and fast to solve, but does not show the change in the plastic zone of the slope during the discounting process. The plastic penetration criterion is not suitable as a criterion for slope instability on its own, but needs to be combined with the unbalanced force rate to be assessed, but it can show the area of shear damage and stretching of the slope. The sudden change of displacement criterion is tedious to solve, but the solution process truly reflects the critical damage state due to the change of slope displacement. For practical conditions such as loess slopes, it is recommended to use the fast computational non-convergence criterion to evaluate the slope stability in combination with the plastic zone penetration and the slope displacement change. [ABSTRACT FROM AUTHOR]