Railway Slopes Research Articles

Predisposition to Mass Movements on Railway Slopes: Insights from Field Data on Geotechnical and Pluviometric Influences

Monitoring natural slopes, embankments, and unstable slopes is crucial to reducing predisposition to mass movements, especially in areas with geotechnical instability and high rainfall. This study proposes a methodology to identify geotechnical and pluviometric triggers of mass movements in railway slopes. It involves registering slopes and embankments along the railroad, recording accumulated rainfall indices, and documenting associated accidents. The experimental program included a cadastral survey at a pilot site on the MRS company’s railway network in the Paraopeba branch, Minas Gerais, Brazil. Surface and subsurface drainage conditions, anthropic interventions, and modifications affecting slope stability were also examined. Additionally, the history of accidents involving geotechnical and regional rainfall indices were incorporated to identify potential triggering events for mass movements. The study found a good correlation between landslide records and geotechnical risk mapping but a low correlation between landslide records and rainfall isohyets. The latter result is attributed to the low density and poor distribution of rainfall data and active pluviometers in the region. Overall, understanding the geological–geotechnical characteristics of slopes and the correlation between accidents and rainfall indices provides valuable insights for predicting potential landslide occurrences.

Resistance characteristics of Y-shaped sleepers for ballasted track under slope influence

The stability of ballasted track is significantly influenced by ballast bed resistance, which inevitably decreases on steeply graded track. Y-shaped sleepers generate considerable ballast bed resistance, but current studies exhibit a research gap in analyzing the performance of resistance variations for Y-shaped sleepers on steep railway slopes. In order to study the mechanical characteristics of the ballasted track with Y-shaped steel sleepers, a discrete element model of the ballast bed for a large-slope railway is established, and its accuracy is validated. The changes of longitudinal and lateral resistance of the ballast bed and the characteristics of the ballast bed resistance of the Y-shaped steel sleeper applied to different slope lines are analyzed. The results show that both the longitudinal and lateral resistances of the ballast bed can be modeled as linearly decreasing with increasing slope, with minimum values of 14.59 kN (longitudinal), 14.33 kN (lateral, tail to head), and 12.09 kN (lateral, head to tail), respectively. The longitudinal resistance provided by the sleeper sides, bottom, and end is minimally affected by the slope. The resistance contributed by the front Y limb increases progressively (from 66 % to 72 %), while the resistance from the rear Y limb decreases (from 11 % to 5 %). The ballast bed support stiffness exhibits a maximum reduction of 18.21 %. Affected by the slope, the longitudinal resistance of the Y-shaped steel sleeper is reduced more than the lateral resistance. The amplitude and influence zone of the longitudinal stress experienced by the ballast are increased with the slope. The study indicates that despite the reduction in resistance characteristics of the Y-shaped sleeper-ballast system due to slope influence, it still maintains high performance.

Digital reconstruction of railway steep slope from UAV+TLS using geometric transformer

Accurate representation of railway slopes, especially those that are steep, is vital for real-time risk perception. Also, temporary structures also present certain safety hazards due to lack of monitoring. Traditional point cloud modeling, employing Unmanned Aerial Vehicle (UAV) or Terrestrial Laser Scanning (TLS), often struggles to simultaneously account for the precision of both surface and overhead models, leading to considerable model distortion, roughness, and deviation. Addressing these issues, A new 3D point cloud modeling algorithm for railway slopes based on a geometric transformer is presented in this paper. This involves an innovative rough point cloud denoising technique leveraging adaptive segmentation, multi-scale denoising, and deep learning point cloud registration. Our approach significantly enhances UAV point cloud accuracy and supplements missing portions of the TLS point cloud dataset occluded by objects block, using data from the UAV point cloud set. An experimental study shows that the score-based denoising algorithm improves precision from 37.44 mm to 8.11 mm for a UAV 3D point cloud. Further, by registering the UAV and TLS point cloud sets using the Geometric Transformer algorithm, the precision of the 3D point cloud was further augmented to 5.11 mm, representing a sevenfold enhancement over the initial UAV point cloud accuracy prior to denoising. Consequently, a high-fidelity 3D point cloud model of steep railway slopes has been created.

A Dynamic Detection Method for Railway Slope Falling Rocks Based on the Gaussian Mixture Model Segmentation Algorithm

Rockfall intrusion detection is crucial for the safety management of railway operations, and video detection methods help reduce deployment costs and improve detection efficiency. Mainstream neural network-based video detection methods have rapidly evolved in recent years but struggle to adapt to complex scenarios such as existing railway slope constructions due to weak generalization ability, low accuracy, and limited information acquisition. Therefore, this paper introduces a dynamic neural network detection model and establishes a dataset for rockfall intrusions in existing railway slope scenarios. The model initially relies on the YOLOv5 neural network, adopting an activation function suitable for the target scenario and addressing overfitting to achieve precise target recognition. Based on the neural network, the model dynamically detects rolling rockfalls by integrating a background subtraction algorithm based on the Gaussian Mixture Model and captures target dimensions using monocular vision technology, thus broadening the dimensions of detection information. Trials conducted on a railway in Shandong, China, demonstrate that the model accurately identifies moving rockfalls along the railway slopes and acquires the dimensions of moving rockfalls, successfully filtering out low-risk targets in the scene.

Initiation mechanism of shallow loess slope sliding under coupling effect of train vibration and rainfall

The large-scale construction and operation of the railway in Northwestern China has resulted in some geological disasters in recent times. Among them, the shallow sliding of the loess railway slope caused by the coupling effect of train vibration and rainfall has been a frequent occurrence, causing heavy losses of life and property. Accordingly, this is a major problem an needs an urgent solution. Therefore, this study used acceleration, pressure, moisture, and displacement monitoring equipment, among others, to conduct physical simulation experiments and theoretical analysis on the instability and sliding process of loess railway slopes under the coupling effect of train vibration and rainfall. The research results indicate that acceleration gradually decreases downward along the slope, and the pore water pressure and volumetric water content increase with the increase in rainfall infiltration. The slope displacement exhibits a phased increase after the initial slip. As vibration energy builds up, the slope bottom undergoes rapid structural damage and tensile shear coupled instability failure, followed by slip. Before sliding, both the crack density and fractal dimension of the slope have an active area, that is, a sliding slope area, which continues to expand upward under the cumulative effect of vibration energy. The failure process is divided into three stages according to the changes in macrodeformation, pressure, water content, displacement, and fractal dimension of the slope model: crack development stage, local liquefaction sliding stage, and slip propagation stage. This research elucidates the initiation mechanism of loess railway slope sliding under the coupling effect of train vibration and rainfall and provides a theoretical basis for predicting loess slope disasters under train vibration and providing adequate warning.

GPS/BDS displacement monitoring of railway slopes based on coloured noise analysis

To analyse the influence of coloured noise in displacement time series on the global navigation satellite system (GNSS) displacement monitoring of railway slopes, and to compare the GPS, BDS and GPS/BDS displacement monitoring results, in the present research the global positioning system (GPS), the BeiDou navigation satellite system (BDS), and GPS/BDS displacement time series data from the GNSS monitoring points on the slopes on both sides of a tunnel entrance of the Changgan High-speed Railway are taken as an example to analyse the displacement of monitoring points before and after removal of coloured noise under the model of white noise + flicker noise. The experimental results show that the flicker noise causes uncertainty around displacement velocity estimation that exceeds the velocity itself, and there is a difference between the GPS and BDS velocity estimation. Eliminating the flicker noise in the displacement time series reduces the uncertainty of the displacement velocity estimation. Most of the uncertainties are less than 0.01 mm/d. Using GPS/BDS technology can help reduce flicker noise and the difference between GPS and BDS speed estimates. That is, the integrated use of GPS/BDS and the colored noise filtering technology in the displacement time series improves the reliability of the slope displacement monitoring results. In addition, the low slope on the side of the railway had a 4 mm displacement in the northerly direction during the selected period. The slope on both sides near the railway has a displacement of 1 to 2 mm in the easterly direction and a rise of about 4 mm in the vertical direction. The displacement of the slope further and higher from the road-bed is not more than 1 mm in both horizontal and vertical directions.

The collision experiment between rolling stones of different shapes and protective cushion in open-pit mines

Though gravel cushions are used worldwide in open-pit mines and railway slopes to control the impact of rolling stones, no universal technical standards have been put in place to guide engineers in their correct design, and few laboratory test results are available with which to characterize collisions between rolling stones and a gravel cushion. We carried out a large number of experiments in which rolling stones made of the same material but differently shaped were dropped from various heights onto cushions with various particle sizes and thicknesses. We investigated the characteristics of the resulting collisions, and the relationships between coefficients of restitution (CORs) of blocks with different shape and release height H, cushion thickness h and particle diameter d are obtained through linear fitting method. Orthogonal testing reveals the relative influence of block shape, release height, and the particle size and thickness of the cushion on the collision characteristics, which can assist engineers in designing a gravel cushion suitable to the distribution and weathering characteristics of rolling stones in a specific area.

Multiple hazard fragility analysis for granular highway embankments: Moisture ingress and scour

Fragility functions express the probability that an asset exceeds some serviceability or limit state for a given level of environmental perturbation or other loadings, to which the asset is subjected. They are important components in the quantitative risk analysis of infrastructure exposed to natural hazards and they have typically been derived for structural assets. It is relatively difficult to derive fragility functions for geotechnical assets, such as highway or railway slopes and embankments, due to their inherent heterogeneity. In this paper, a generic granular highway embankment is modelled using the finite element method, considering various groundwater profiles and scour depths at the toe to quantify the deformation of the road surface. A probabilistic assessment of the magnitude of deformation and the groundwater level and scour depth is undertaken to derive fragility functions for the prediction of damage to assets exposed to these multiple hazards. The process of fragility function derivation is explained, uncertainty values are derived, and various regression methods are undertaken. This study is a first attempt to provide a basis for the prediction of slope deformation, and hence of damage, due to moisture ingress and scour, which can be aggravated by climate change. This can be used for the assessment of existing assets, and the design of new ones in the pursuit of more resilient transport networks, as well as for other assets such as levees, dams and other similar earthworks, with some limitations.

The vegetation on railway embankments of the Kursk region

The present paper deals with the classification of the plant communities developed on the railway embankments in Kursk region. This type of vegetation is still poorly studied in Russia although some floristic information is available for various regions. Kursk region is located between 50°542–52°262 N and 34°052–38°312 E. Its area is 29 800 km2. Zonal vegetation is represented by broad-leaved forests on dark-gray forest soils and meadow steppes on chernozems. The vegetation of the railway embankments was being studied in Kursk region since 2003. Railway embankment sections were surveyed in the city of Kursk, the towns of Dmitriev, Lgov, Oboyan, Rylsk, Shchigry, and urban settlements of Konyshevka, Kshenskiy, Ponyri, Pristen. The upper parts of railway embankments, slopes and nearby sites, stations, and areas between roadbeds were studied. Classification according to Braun-Blanquet approach, with the use of “deductive method” (Kopeсký, Hejný, 1974), is based upon 120 relevés. The data were treated by software package IBIS 7.2 (Zverev, 2007). The names of the higher syntaxa are given according to “Vegetation of Europe…” (Mucina et al., 2016). Direct ordination of relevés by soil moisture and nitrogen content factors (scales after H. Ellenberg et al. (1992)) was conducted to distinguish ecological specificity of the communities on railway embankment and those outside railways. The vegetation of the urbanized territories under strong man impact in general and in particular around railway stations is highly diverse. The plant cover regularly destroyed by herbicides re-establishes in different ways depending on the distance from the stations. The mostly diverse are communities on the railway slopes wh ere the late successional stages are present due to the poorer pressure, These communities were compared with the undestroyed ones occurring beyond railways (Arepieva, 2015). Syntaxonomy of railway embankment vegetation in Kursk region includes 3 classes, 4 orders, 4 alliances, 9 associations, 2 subassociations, 4 variants and 3 communities. Phytocoenoses of the railway embankments are formed under specific conditions resulting in their floristic composition and structure being different from those beyond the railways due to the man impact, moisture, trophicity and substrate mechanical composition. The suggested syntaxonomy of the vegetation of railway embankments is not yet complete. New syntaxa would be established along with the data accumulation.

System reliability of slopes using multimodal optimisation

Many engineered and natural slopes have complex geometries and are multi-layered. For these slopes traditional stability analyses will tend to predict critical failure surfaces in layers with the lowest mean strength. A move toward probabilistic analyses allows a designer to account for uncertainties with respect to input parameters that allow for a more complete understanding of risk. Railway slopes, which in some cases were built more than 150 years ago, form important assets on the European rail network. Many of these structures were built at slope angles significantly higher than those allowed in modern design codes. Depending on the local geotechnical conditions these slopes may be susceptible to deep-seated failure; however, a significant number of failures each year occur as shallow translational slips that develop during periods of high rainfall. Thus, for a given slope, two potential failure mechanisms might exist with very similar probabilities of failure. In this paper a novel multimodal optimisation algorithm (‘Slips’) that is capable of detecting all feasible probabilistic slip surfaces simultaneously is presented. The system reliability analysis is applied using polar co-ordinates, as this approach has been shown to be less sensitive to local numerical instabilities, which can develop due to discontinuities on the limit state surface. The approach is applied to two example slopes where the complexity in terms of stratification and slope geometry is varied. In addition the methodology is validated using a real-life case study involving failure of a complex slope.

Safety factors and limit states analysis in geotechnical engineering: Discussion

The paper is a further valuable contribution by Dr. Meyerhof on the subject of safety factors and limit states design in geotechnical engineering. It is understood that the paper also represents the basic approach that will be adopted with respect to limit states design in the second edition of the Canadiaiz foundation engineering manual. The load and resistance factors given in Table 2 of the paper are indicated to agree with those specified in the National Building Code of Canada (1985) and in the Ontario Highway Bridge Design Code (1983), respectively. They also agree very closely with those given in the Danish Code of Practice for Foundation Engineering (1978). The author indicates that the total and partial safety factors for geotechnical analyses 'are interrelated, and that the partial factors suggested for use in limit states design have been obtained by calibration with conventional geotechnical analyses. It is apparent from the paper that a constant value for the overall factor of safety is obtained only if the partial factor, f+ for example, varies with the value of the friction angle, 4'. ~ l t e r n a t i v e l ~ , if fm is held constant, then the overall factor of safety will not remain constant. The writer has examined the variation of the overall factor of safety for simple slopes, cantilevered rigid retaining walls, flexible sheet pile walls, and shallow foundations, designed to satisfy the ultimate limit states criterion using the author's recommended partial factors and the results are bgeflv outlined herein. The design of simple slopes using shear strength parameters in terms of total stress may be carried out using Taylor's stability charts (d, = 0 analysis). For this particular case the author recommends a partial factor, f, = 0.65, which is equivalent to an overall factor of safety, F, of 1.54 on cohesion or height, which compares closely to the overall factor of safety of 1.5 employed for the design of such slopes in conventional practice. The design of simple slopes with uniform soil and ground water conditions using an effective stress approach may be carried out using the Bishop and Morgenstern (1960) stability coefficients. The slope inclinations obtained using the limit states analyses show increasing overall factors of safety with increasing pore water presswes, from 1.25 with r, = 0 to about 1.8 for ru = 1.5. It is customary in conventional practice to select an overall factor of safety, F, which is dependent upon the loading conditions and the consequences of having a slope failure-occur. Highway, railway, cut, and embankment slopes tend to be designed using a lower overall factor of safety than would be employed for a slope where a structure is to be constructed near the top or base. The recommended limit states