Bed Thickness Research Articles

Numerical Simulation of Dam-Break Flood Routing and Sediment Erosion and Deposition Under Different Rainfall Conditions

Landslide dam is a natural dam body formed by collapse, landslide and debris flow. The flood caused by dam break will cause significant risk to the downstream of the dam. Under the effect of rainfall environment, the erosion and deposition rate of flood and sediment in the downstream of the dam will be affected. This paper takes Tangjiashan dam as the research object, establishes the digital elevation model of the downstream channel according to the field survey and geological data, establishes the two-dimensional unsteady hydrodynamic model with the help of MIKE 21, explores the material movement law of the dam break flood in the downstream channel, and analyzes the influence of rainfall on the distribution of sediment deposition rate and sediment transport rate in the dam break flood The variation of riverbed thickness and the influence of flood sediment concentration rate. Based on the rainfall of dam break flood, this paper studies the sediment erosion and deposition law of dam break flood under different rainfall conditions. The results show that the occurrence of rainfall can significantly increase the sediment holding capacity of dam break flood. Under different rainfall intensities; The sediment deposition rate in floods will be affected by rainfall. The sediment deposition rate under the condition of rainfall is higher than that under the condition of no rainfall; Increasing rainfall intensity will increase the sedimentation thickness of the river bed near the collapse of the Tangjiashan dam, such as the collapse of the Shuimogou ditch. Based on the relevant research conclusions under different rainfall conditions, this paper could provide significant theoretical guidance for the flood erosion law of dam breaks and downstream rescue work.

Control of the Internal and External Staggered Distance of Coal Mining Face to the Water‐Conducting Fissures in the Overlying Strata of the Near Coal

In Northwest China, rainfall is low, water resources are scarce, and the ecological environment is fragile. For shallow‐buried and close‐spaced coal seams with a thickness of upper coal bed >60∼70 m, the water‐conducting fissures of the overlying rock will not penetrate the water‐isolating layer after the upper coal seam is mined; the internal and external gap angles of the water‐conducting fissures are not generated from the water‐isolating layer. We set out to explore the critical internal and external dislocations for the second significant development of water‐conducting fissures in the overlying rock after coal mining under control. A calculation model for the critical internal and external staggered distances of coal mining face in shallow‐buried and close‐spaced coal seams is established, the calculation formula is given, and the calculation formula for the critical seam mining ratio under the condition of internal staggered mining mode is given. Numerical simulation performed by UDEC methods: taking the overburden strata in the shallow‐buried and close‐spaced coal seam mining area of Shigetai Coal Mine as a prototype, it was verified that the critical internal and external offsets of the coal mining face in shallow‐buried and close‐spaced coal seams have a significant effect on the overlying water flow cracks in the mining of the lower coal seam. For the feasibility of developmental control, according to the engineering geological conditions of Shigetai, through the calculation method of external staggered distance, it is concluded that the distance of the open cut of the lower coal face and the upper coal face is only 21∼27 m, which is much smaller than the water barrier. It does not produce the critical distance of the water‐conducting cracks. Therefore, in the process of mining the lower coal seam, the water‐proof layer will produce water‐conducting cracks, lose its water‐proof performance, and cause water loss. This is also the cause of the water inrush accident in Shigetai Coal Mine.

Effects of Bedding Geometry and Cementation Strength on Shale Tensile Strength Based on Discrete Element Method

To study the effects of anisotropy and heterogeneity on the shale failure mode and tensile strength, Brazilian splitting tests were performed from both directions of the bedding and layer thickness. Layers containing different bedding and loading angles and layer thicknesses were obtained separately. The results show that, at 0° and 90° angles, the shale cracks grow “linearly”; at 15°, the shale cracks have “arc type” growth; and at 30°–75°, the shale‐splitting displays “broken line” crack propagation. The tensile strength from 0° to 90° exhibits an increasing trend. Water has a significant softening effect on the tensile strength of shale—the higher the water content, the lower the tensile strength. In addition, a 3DEC numerical simulation was used to simulate the tests, establishing shale specimen particles with random blocks. In the shale disc, uneven parallel bedding and uniform parallel bedding were set up with different loading angles and layer thicknesses to generate simulated stress‐displacement curves, and the effect of layering on shale cleavage was analyzed from a mesoscopic perspective. The tensile strength of shale with uniform parallel bedding was found to be higher under the same conditions, which is consistent with the experimental results. By comparing the experimental and simulation results, from both the macro‐ and mesoperspectives, the Brazilian splitting crack growth of shale is affected by bedding, displaying a process from disorder to order. This study is of great significance for further exploration of the mechanical properties of shale under loading failure.

Demographic and clinical profile, surgical outcome, and quality of life in patients who underwent bilateral lamellar corneal grafts.

Purpose:Lamellar corneal grafts have revolutionized the management of corneal blindness by replacing only the disease specific corneal layers. To the best of our knowledge, there is no study in literature describing the outcomes of bilateral lamellar keratoplasty in the Indian population. The aim of this work was to study the demographic profile, surgical outcomes, and quality of life in patients who underwent bilateral lamellar keratoplasty and to assess the correlation between these three.Methods:An observational cross-sectional study was conducted on 47 patients who underwent bilateral deep anterior lamellar keratoplasty (DALK) (n = 31) or descemet stripping automated endothelial keratoplasty (DSAEK) (n = 16) with a minimum follow-up of 6 months after the second surgery. Demographic parameters were collected by interview, surgical outcomes by clinical examination, and quality of life by a questionnaire.Results:A total of 47 patients were evaluated, women 42.56%, (n = 20) and men 57.44% (n = 27) with 38.3% being in 18–30 years age group and 23.4% above 60 years; 17.02% patients had a good socioeconomic status (score >60) and 61.70% had poorer socioeconomic status (score <50). Quality of life score (VR-QoL) was ≥50 in 82.9% patients and ≥70 in 14.89%. No significant association existed between VR-QoL scores and demographic factors. However, statistically significant association existed between VR-QoL and age of patient (P < 0.05), postoperative vision (P ≤ 0.05), and contrast sensitivity (P ≤ 0.01).Conclusion:Bilateral lamellar corneal grafts provide satisfactory visual outcomes compatible with day-to-day functioning. VR-QoL has a direct correlation to the age, visual acuity, contrast sensitivity, and inverse correlation with lenticule thickness in DSAEK and residual bed thickness in DALK.

Residual shear strength of shales from the Gemas Formation based on ring shear tests

Fresh, dark grey to black, shales with minor sandstones of the Triassic Gemas Formation outcrop at the slope cut between Km 81.30 and 81.05 (southbound) of the North-South Expressway near Ayer Hitam in Johore State. The beds strike 165o with eastward dips of 35o to 43o and have thickness of between 0.2 and 1.5 m. Over-lying the fresh bedrock along an irregular boundary is a bleached zone, some 14 to 18 m thick, comprising light grey to white, in situ oxidized shales and sandstones. Three samples were collected from a thick shale bed; fresh samples A and B at 18 m and 15 m depth, respectively, and a bleached shale sample C at 11 m depth. All samples were air dried, finely ground, and then passed through a wire mesh sieve with 180 μm aperture sieve. The remoulded samples were tested with the Bromhead ring shear apparatus, employing the pre-shearing test procedure with multi-stage loading. Plots of shear stress versus cumulative horizontal shear displacement under low normal stresses (&lt;150 kPa) yield failure envelopes with residual friction angles of 27.4o, 27.4o and 27.9o for samples A, B, and C, respectively. Under moderate to large normal stresses (150-350 kPa), plots of shear stress versus linear displacement sometimes slope upward due to increased friction as a result of sample extrusion and settlement of the top platen. It is concluded that the pre-shearing test procedure with multi-stage loading is best suited for low to moderate, effective normal stresses (&lt;250 kPa). Based on the test results, the residual friction angle for shales from the Gemas Formation is between 27o and 28o.

Development of thermal model for the determination of SLM process parameters

In this study, a mathematical model is developed for determining the process parameters used in the manufacturing process of powder materials with selective laser melting method. Although the studies carried out to date cover detailed modeling studies including three-dimensional and time-dependent situations, obtaining quite different approaches from experimental results has led to the idea that a change should be made in the construction of the mathematical problem. Therefore, different from other studies and for the first time, the Eigen-function expansion method was used in the analytical solution of the selective laser melting thermal model. The developed mathematical model includes the steady-state solution with the appropriate boundary conditions of the 2-D non-homogeneous heat equation. The mathematical model was first solved analytically with the Eigen-function expansion method, and the function obtained as a result of the solution was introduced into the MATLAB software. The parametric study was performed numerically over laser power, laser spot size and powder bed thickness. With the developed model, the solution was converged in 30 s and 11.5% more accurate with respect to experimental results were obtained in width, 29% in depth and 3% in temperature as compared to other analytical models exist in the literature.

Badush Dam: Planned And Designed As A Protection Dam, Nw Iraq

Badush Dam is uncompleted combined earthfill and concrete dam, it is located on the Tigris River. The dam is planned and designed to be a protection dam downstream of the already existing Mosul Dam to protect population and infrastructure downstream of Mosul Dam. Thisa is attributed to the safety concerns of Mosul Dam which suffers from severe karstification in its foundation due to the presence of thick gypsum beds. The safety of Mosul Dam is a matter of debate since its construction and commissioning in 1986. The construction of Badush Dam started in 1988 and suspended in 1991, although (30 – 40) % of the dam was already built. The geological setting of Badush Dam is almost similar to that of Mosul Dam. Therefore, the foundation of Badush Dam will suffer from the same problem which is karstification because they are located on gypsum beds which are the same rocks under the foundations of Mosul Dam. The thin inclined clay core and foundation treatment works indicate clearly that Badush Dam is designed to have temporary nature which is to contain the volume of Mosul Dam wave (11 × 11km3) in case of collapse of Mosul Dam and to pass the wave downstream without flooding.

Preliminary investigations of rocks and soil at the lower reach of Al-Shor Wadi for water harvesting

The last four decades weather forecasting data marks the precipitation declination and increase dry years, in addition to the desertification migration on the west and northwestern Mosul city. This led to studying the Al-Shor Wadi area to try to make use of the karstic spring water flow through it and to harvest the rainfall flow water. These need to select the best site to construct a dam taking into consideration the geological and geotechnical characteristics of both dam site and lake behind. The dam site appears to be appropriate relying on the large thickness and frequencies of the marl bed, the restriction of gypsum bed thicknesses and frequencies as well as, of the approximate nill karstification.

Novel coalescer design with bed of waste polymer fibers for liquid aerosol separation

This paper presents the development and optimization of a novel self-cleaning coalescer with drainage section, for liquid aerosol treatment. Four different waste polymer fibers were investigated as filter bed material for the novel coalescer: polyurethane (PU), polyethylene terephthalate of different origin (PET1 and PET2) and polypropylene (PP). Metal working fluid (MWF) mist from 6% of MWF emulsion was applied as liquid aerosol. Different bed thickness with and without preloading methods were tested to find an optimal separation efficiency for acceptable pressure drop. The applied air velocity through the coalescer was varied from 1 m/s to 5 m/s. Experimental results show that all investigated polymer materials could be successfully used as filter bed in the newly developed coalescer. The total separation efficiency is over 96% (between 96.73 and 99.98%) for almost all investigated conditions, except at the air velocity of 1 m/s, for PU and PP filter bed when it is 88.55% and 91.14%, respectively. Maximal separation efficiency for fraction 1 (0.2–0.3 µm) and 2 (0.3–1 µm) is 81.36% and 99.71%, respectively. The coalescer realizes maximal pressure drop of 4.75 kPa at 5 m/s air velocity in wet-steady state. The findings indicate that the novel coalescer could be easily optimized depending on inlet air quality and permissible level of PM1 in the outlet air.

A three-phase model for simulation of heat transfer and melt pool behaviour in laser powder bed fusion process

Laser powder bed fusion (LPBF) is one of the most promising additive manufacturing technologies to fabricate high quality metal parts. In this work, a three-phase model based on the volume of fluid (VOF) is employed to investigate the heat transfer and melt pool behaviour in LPBF. Surface tension, Marangoni effect and recoil pressure are implemented in the model, and heat adsorption, reflection and transmission are fully considered. The results show that the melt pool dimension and its shape are controlled by laser power and scanning speed. Metal powders at the bottom layers may be not fully melted, and for larger layer thickness of the powder bed, porosities caused by the trapped gas can form. The gas originated from bulk powders can dissolve, coalesce, and be squeezed in the melt pool. It is demonstrated that the model can capture the main features of powder melting and solidification in LPBF process.

Bed type and flow mechanism of deep water sub-lacustrine fan fringe facies: an example from the Middle Permian Lucaogou Formation in Southern Junggar Basin of NW China

Submarine or sub-lacustrine lobe deposits are important reservoirs, but the fan fringe deposits form heterogeneities within deep water fan deposits. Fan fringe facies records the complex sediment gravity flow types. By understanding of the bed types and flow mechanisms, we can identify the fan fringe deposit, which aids in the reconstruction of deep water fan and reservoir evaluations. The Jiucaiyuanzi and Dalongkou sections in the West Bogda Mountains preserve well-exposed 536-m and 171-m thick successions, respectively, of a deep water lacustrine depositional system from the Middle Permian Lucaogou Formation. Bed types of the Lucaogou Formation include high-density turbidite, low-density turbidite, incomplete Bouma-type turbidite, hybrid event beds, and slump deposits. The Lucaogou Formation is interpreted here as a fan fringe facies due to the thin bed thickness that characterize turbidites and hybrid event beds, as well as the predominance of the isolated sheet architecture. Previous studies suggest that these deposits were considered as deposited in a deep water setting due to the absence of wave-related structures. The presence of abundant mud clasts in massive medium-coarse grained sandstone beds reflects the significant erosional capability and interactions between high-density turbidity currents and lake floor. The fan fringe facies here contains amalgamated and thick-bedded homolithic facies (~ 30%) and thin-bedded heterolithic facies (~ 70%). The examination of the bed type is of wider significance for facies prediction and reservoir heterogeneity in the sub-lacustrine fan fringe facies.

Petrology of oolitic ironstones of Ashumaysi Formation of Wadi Fatima, western Arabian Shield, Saudi Arabia

The present study concerns Oligo–Miocene oolitic ironstones of the Ashumaysi Formation between Jeddah and Makkah in the western part of the Arabian Shield, western Saudi Arabia. The Ashumaysi Formation contains oolitic iron ore as 2–3 m thick beds. The formation is exposed along the western margin of Wadi Ashumaysi. It dips toward the east and unconformably overlies Precambrian rock and conformably underlies a Miocene basalt flow of the Sita Formation.The Ashumaysi ironstones are mainly hematitic sandstone and oolitic ironstone. The oolitic ironstones vary in color (reddish, brownish, yellowish, or violet). Petrographic analysis indicated that the ironstones are composed of different shapes of ooids (ooliths), pelloids, and rarely pisoids (pisoliths) within ferruginous cement and matrix, which consists of clay minerals with fine to medium grained quartz XRD with EDX analysis of representative samples indicated that hematite, goethite, chamosite, and quartz are the main components of the oolitic ironstone.The main processes responsible for the formation of these oolitic ironstones are progressive diagenetic dehydration and recrystallization of the amorphous ferrous hydroxides and the formation of oolitic and pisolitic goethite and hematite within different fabrics.

Effect of packing structure on mechanical properties of the pebble beds and the probability of particle crushing

Abstract The tritium ceramic breeder pebble bed, used for tritium breeding and in nuclear fusion reactor, is a key constituent of helium cooled solid breeder blankets. The mechanical properties of the pebble beds, along with the integrity of the particles are very important for the extraction of tritium and safe operation of the solid blanket. In this paper, analysis is carried out on the effect of packing structure, with varying bed thicknesses and particle smoothness, on mechanical properties and the probability of particle crushing. Pebble beds are randomly packed by a single type of Li 4 SiO 4 particle, 1 mm in diameter. It is found that when the thickness of the Li 4 SiO 4 pebble bed (ranging from 15 mm to 25 mm) becomes thinner, or the coefficient of friction (ranging from 0.1 to 0.6) increases, the strain of the pebble bed and the probability of particle crushing increases under the same mechanical load. Pebble beds with different packing structures have the same probability distribution function of normalized contact forces. The results could serve to characterize the tritium pebble beds and to optimize the design of helium cooled solid breeder blankets.

Green Glauconitic Marl Bed As A Sequence Stratigraphical Key For Interpretation Of Contact Between Qamchuqa And Bekhme Formations In Bekhal Area, Kurdistan Region, NE Iraq

This study incorporates a study of stratigraphy and sedimentology of the green glauconitic marl bed between Qamchuqa and Bekhme Formations in selected section of the Iraqi Kurdistan region. The studied area is located in Gali Garukaju near Rwanduz in Erbil Governorate, northeastern Iraq. Instead of Basal Conglomerate bed, the thin beds of green glauconitic marl occurs along the contact between Qamchuqa and Bekhme Formations in the studied section. Six samples were collected from this section, two samples for XRD and four samples for petrography analysis. Samples for XRD and petrographic analysis were taken from green glauconitic marl beds at the contact between two formations and from upper contact of Qamchuqa Formation and lower contact of Bekhme Formation. XRD analysis data proved the presence of glauconite in green marl bed. General petrographic observations of other remaining four samples in thin sections reveal that the upper contact of Qamchuqa Formation and lower contact of Bekhme Formation are dolomite and dolomitic limestone. The dolomite bed represents type 1 or type 2 depending on the thickness and extension of dolomite bed. Color, morphology, maturity and abundance of glauconite grain were the dominant factors used in the determination of the surface between the two formations. The result emphasizes that the surface was not a gradational surface consisting of low stand and condensed system tract (LST/CS). Two factors, color and morphology, of glauconite grains were analyzed by binocular microscope under reflected light. The morphology of most glauconite grains in this section is ovoidal and tabular with green to dark green in color. Based on these two factors the glauconite grains were within stages 3 and 4 of McCracken et al. (1996) classification and can be interpreted as evolved and high evolved in view of maturity. The presence, increase in concentration and mature grains of glauconite (evolved and high evolved) in marl beds at lower part of Bekhme Formation indicate transgressive or maximum flooding surfaces.

Supergene sulphuric acid speleogenesis and the origin of hypogene caves: evidence from the Northern Pennines, UK

AbstractThe maze caves of the Northern Pennines are rectilinear joint‐controlled networks of predominantly tall vertical rifts developed on one level towards the top of a ~20 m thick limestone bed; they were all intersected by underground mines and have no relationship to the present landscape. Passage walls commonly have large, non‐directional scallops; speleothems are uncommon. The caves were previously identified as hypogene in origin, i.e. formed by groundwater ascending from depth, but reassessment of their origin using published data shows that they lack diagnostic hypogene features (rising wall channels, ceiling channels, ceiling cupolas and dome‐pits), and the low permeability strata above and below the limestone bed greatly restrict vertical groundwater flow through the caves. Instead the maze caves were dissolved by the sulphuric acid released by oxidation of iron sulphides (and perhaps chalcopyrite) in the mineralized veins adjacent to all these caves; passage sizes decrease away from the veins and gypsum encrusts the walls of one cave. The maze caves were not formed by vertical groundwater flow, and dissolution was focussed in a relatively small area of limestone beneath an impermeable confining layer. The caves began to form when river incision due to the probably Late Cenozoic uplift of northern England exposed the iron sulphides to weathering and oxidation.The process that formed the maze caves is here termed supergene sulphuric acid speleogenesis, because generation of the acidity was due to near‐surface supergene sulphide oxidation, and differentiated from hypogene sulphuric acid speleogenesis, where the source is at depth beneath the cave.To clarify usage of the term hypogene, it should be restricted to Palmer's geochemical definition (Speleogenesis: Evolution of Karst Aquifers, eds Klimchouk et al., National Speleological Society: Huntsville, AL, 2000; 77–90): dissolution by a deep‐seated source of acidity. Caves dissolved by ascending groundwater containing carbonic acid with a near‐surface origin, e.g. on the rising limb of a phreatic loop, are better identified as epigene. © 2020 John Wiley &amp; Sons Ltd

Research on Design Parameters and Fatigue Life of Tunnel Bottom Structure of Single-Track Ballasted Heavy-Haul Railway Tunnel with 40-Ton Axle Load

The coupling calculation model of tunnel and surrounding rock is established by the finite difference method, and the main design parameters of lining structure of single-track ballasted tunnel under 40-ton axle load, heavy train load, are studied in combination with cumulative damage mechanism of surrounding rock at tunnel bottom and the fatigue life characteristics of concrete structure at tunnel bottom. The results show that (1) inverted arch shall be set in sections of III-grade and above. Whether an invert is set in sections of II-grade and below shall be determined according to lithology and groundwater conditions. When the surrounding rock condition is good and the tunnel bottom structure (without invert structure) is adopted, the thickness is recommended to be more than 20 cm, and the concrete strength grade should not be lower than C35. (2) Connection mode: the inverted arch and side wall of the tunnel should be connected in sequence to reduce the stress concentration and improve the stress state of the connection part between the inverted arch and the side wall. (3) It is suggested that the rise-span ratio of invert of single-track tunnel should be 1/6 ∼ 1/8; the larger value should be taken when the surrounding rock condition is poor and the small value should be taken when the surrounding rock condition is good. (4) The thickness of inverted arch is recommended to be no less than 20 cm under the condition of V-grade surrounding rock, to be no less than 15 cm under IV-grade surrounding rock, and to be no less than 10 cm under the condition of III-grade surrounding rock and II-grade surrounding rock sections requiring inverted arch. (5) The recommended value of bedding thickness meeting the design service life is 20 cm under the condition of II-grade surrounding rock.

Extending the Boussinesq model for impacts in granular media

Granular impact phenomena have implications in many areas. A fundamental problem deals with the mechanical response of a granular medium under external loads, such as those derived from the impact of a rigid object on the top of the medium. Here, the load changes its magnitude and intensity during the impact, being also applied in much shorter intervals than those of a static load, where the Boussinesq model is usually valid. This dynamic has been poorly addressed in the literature, a void to which this study aims to contribute, where we measure the pressure distribution transmitted at the bottom of a uniform, dry granular layer under the action of gravitational impacts of a steel sphere of fixed diameter. Exploring different bed thicknesses and drop heights, it is found that the structure of this distribution follows a similar form to the Boussinesq model, which was proposed initially for static conditions. This surprising result opens up several questions and future research challenges that could help validate or refute this model in other scenarios.

Optimal bed thickness and effective size for improving wastewater quality for irrigation

With the increased use of wastewater for irrigation, there is the need to reduce the contaminant levels in wastewater. The slow sand filtration (SSF) is one such method that can be used to improve wastewater quality. However, the treatment quality depends among other factors on the depth of sand bed and the effective size. Acquiring sand of a particular effective size is becoming increasing difficulty and, therefore, this study sought to investigate over a specified area, the optimal depth and effective size that will be able to get rid of contaminants in wastewater. In separate experiments, three depths (30 cm, 40 cm and 50 cm) and two effective sizes (0.27 mm and 0.45 mm) were set up to investigate their effectiveness in removing Faecal coliform, E. coli and heavy metals (Pb, Cu and Fe) for wastewater from a peri-urban drain used for irrigating vegetables. Results showed that a minimum sand bed thickness of 40 cm and an effective size of up to 0.45 mm reduced the contaminants tested significantly, wastewater from the drain can be treated. It must be mentioned that the finer sand (0.27 mm) had a slightly better removal efficiency. This implies that the extra cost of acquiring sand of relatively smaller effective size and a higher bed depth with the aim of improving wastewater quality can be saved. Further investigations are being carried out on the combined effects of the optimal sand bed depth and effective size.

Bed topography of Princess Elizabeth Land in East Antarctica

Abstract. We present a topographic digital elevation model (DEM) for Princess Elizabeth Land (PEL), East Antarctica. The DEM covers an area of ∼900 000 km2 and was built from radio-echo sounding data collected during four campaigns since 2015. Previously, to generate the Bedmap2 topographic product, PEL's bed was characterized from low-resolution satellite gravity data across an otherwise large (&gt;200 km wide) data-free zone. We use the mass conservation (MC) method to produce an ice thickness grid across faster flowing (&gt;30 m yr−1) regions of the ice sheet and streamline diffusion in slower flowing areas. The resulting ice thickness model is integrated with an ice surface model to build the bed DEM. Together with BedMachine Antarctica and Bedmap2, this new bed DEM completes the first-order measurement of subglacial continental Antarctica – an international mission that began around 70 years ago. The ice thickness data and bed DEMs of PEL (resolved horizontally at 500 m relative to ice surface elevations obtained from the Reference Elevation Model of Antarctica – REMA) are accessible from https://doi.org/10.5281/zenodo.4023343 (Cui et al., 2020a) and https://doi.org/10.5281/zenodo.4023393 (Cui et al., 2020b).

A complex slide-buckling-toppling failure of under-dip soft rock slopes

This study investigates a complex slope failure that occurred in Chongqing Xi railway station. The studied slope belongs to a under-dip shale slope. Onsite surveys and UDEC numerical modelling were conducted to describe the deformation characteristics and potential failure mechanism of this slope. The simulated results suggest that sliding, buckling and toppling can occur in the deformation process, which is verified by the actual deformation characteristic of the slope and monitoring results. Moreover, the effects of bedding dip angle, slope angle, bed thickness on the deformation characteristics of the slope were also investigated with UDEC models. Finally, the possible slope structure for occurrence of slide-buckling-toppling failure and several numerically validated remedial measures were proposed.