Surface Slope Research Articles

Numerical study on the failure evolution of rock slopes containing multi-flaws by strength-based fracture method

In this study, we adopt the proposed strength-based local maximum stress (SLMS) criterion to calculate the crack propagation of tensile and shear cracks in a plate with two parallel closed flaws at different rock bridge inclinations (β) under compression. The effect of β on the failure mode of rock bridges was investigated. Then, we modeled the three-section landslides caused by crack propagation under different friction coefficients to validate the effectiveness of SLMS in modeling crack propagation in slopes. Finally, the formation of sliding surfaces in four specific rock slopes with multi-flaws was modeled to investigate the effect of flaw distribution on the depth and shape of sliding surfaces of slopes. Results indicate that flaws located in the middle of the slope have a significant effect on the failure mode and the depth of the sliding surface at this location. Due to the small increments of displacement during the failure process of the slope, which are difficult to monitor, displacement monitoring methods are ineffective for landslide early warning. The instability of the rock slope is caused by the initiation, propagation, and coalescence of cracks, therefore, real-time monitoring of the micro-failure accumulation in the slope is beneficial for early warning of landslides. Moreover, the variation of contact status of crack surfaces during the formation of slope sliding surfaces was analyzed, and the effect of sliding surface formation on contact sliding distance and contact gap distance of crack surfaces was investigated.

RECREATIONAL ASSESSMENT OF MORPHOMETRIC INDICATORS OF THE BAZUM RIDGE

The purpose of tourism assessment of the terrain is to contribute to the economic development of the area under study. When tourism was chosen as a direction contributing to the development of Armenia’s economy, interest in the recreational value of the area began to increase. In the article, a recreational evaluation of the format (morphometric) relief indicators of the Bazum mountain range was made, which was carried out based on the indicators of fragmentation depth, fragmentation density, surface slopes and orientations. Large-scale thematic maps of the area were made, and analysis of these maps was performed. The analysis of this and similar nature allow not only to assess the possibilities of tourism development in Lori Region, but also to outline the development prospects of this branch. A scale was built for the assessment, and ATC technologies were used. For the purpose of calculating the indicators, we used the opportunities provided by GIS, the ArcGIS 10.5 software system was used. The purpose of the research is to evaluate the morphometric indicators of the relief of the Bazum mountain range from the point of view of recreation development.

Determining of Affect Levels on Agriculture and Livestock of Factors Such as Landforms, Soil Types and CORINE Land use/cover According to Analytic Herarchy Process(AHP) in Basin of Kesis Stream(Southern of Türkiye)

Abstract
 Human-being has always continued its efforts to recognize and benefit from the natural environment in which it has lived since its existence, and it continues this struggle today. However, over time, human beings have begun to realize that the natural processes they encounter in the natural environment have more than one cause. Today, researchers have developed various methods to determine the degree of impact of events that occur due to more than one reason. One of these methods is the Analytical Hierarchy process(AHP). In this study; Landforms, soil types and the effect levels of CORINE land use/cover on agriculture and livestock were investigated according to the AHP in the Kesis Stream Basin. In the research; Methods such as Geographical Information Systems (GİS), AHP, Digitization formula, remote sensing (RS) were used. Based on these methods, the study was embodied with various figures, tables and graphics suitable for the purpose of the study. According to this study, in the Kesis Stream Basin; 25.992% of landforms, 41.260% of soil types, and 32.748% of CORINE land use/cover on livestock activities were determined. Similarly, in the basin; Landforms had effects on agricultural activities with 19,580%, soil types 31,081%, CORINE land use/cover 49,339%. Here; While land use/cover on agricultural activities and soil types on livestock are in the first place, landforms have the least effect on both. In the basin, which has a rugged and karstic structure; As seen in figure 3/A, while agricultural areas such as range of deposits, polje, and uvala correspond to the 'very important' classification, the importance of slope surfaces and other areas gradually decreased. In Figure 3/B, while agricultural fields and slope surfaces have a 'very important' and 'significant' effect on livestock activities, the importance of peak and high flats and rocky steep surfaces is the least. It can be said that the findings obtained as a result overlap with the current realities of the basin and are successful.

Analisis Stabilitas Lereng dengan Metode Bishop pada Proyek Geotechnical Investigation Jalur Transportasi Pelabuhan Batubara Marangkayu Kabupaten Kutai Kartanegara

A slope is a surface that has a slope and forms a certain angle to the horizontal plane and is not protected. The slope and angle formed cause the slopes to have differences in surface height. Differences in slope surface height result in forces acting to push, and also forces in the soil acting to resist or resist, so that the position of the soil remains stable. The stability of a slope is expressed in the slope safety factor which is obtained or obtained by comparing the holding force and the pushing force. Based on topographic data of ground investigation drilling points on the Marangkayu Coal Port transportation route, Kutai Kartanegara Regency, it is known that there are several drilling points with soil conditions in the form of slopes or hills, so it is predicted that they could cause the potential for landslides because these points will become transportation routes for loading and unloading materials. coal. The aim of this research is to determine the slope safety figures, and to obtain a safe slope with the original slope conditions. The method used to analyze slope stability in this research uses Geostudio Slope Bishop method software. The results of the analysis of the original slope conditions at the OLC-FBH-03 and OLC-FBH-06 test points showed that the slope safety value was obtained with the result being that the slope condition was safe from landslides (FK>1.25). With this, it can be concluded that the Marangkayu Coal Harbor transportation route, Kutai Kartanegara Regency is safe from landslides.Keywords: Bishop Method, Geostudio Slope, Slope Stability, Slope Safety Value

Similarity Model Test on Rainfall Scouring Mechanism of High-Speed Railway Subgrade Slope

The subgrade slope, when exposed to the natural environment for a long time, is easily affected by rainfall scouring, which leads to a large loss of filling materials and soil sliding, affecting the stability of the subgrade slope. In this paper, the model test of a high-speed railway subgrade slope under rainfall scouring was conducted to quantitatively study the occurrence and development process of subgrade slope erosion. Compared with the model test results and the theoretical results, the incipient flow velocity formula of coarse-grained soil was verified. Then, the curve of rainfall intensity varied with the incipient particle size under different rainfall intensities, slope gradients and soil particle grading conditions was analyzed. Results show that during rainfall scouring, the smaller the particle size, the earlier the scouring erosion occurs. In addition, the soil particles on the slope bottom were scoured more severely than those on the slope upper. With the increase in rainfall intensity, slope gradient, and the change in soil particle gradation (removing the minimum particle size), the incipient flow velocity of soil particles on the slope will be reduced. The curve of the rainfall intensity varied with the incipient particle size, which plays an early warning role in the analysis of slope erosion stability and reflects the particle size range of the scouring erosion incipient on the slope surface under different rainfall intensities, providing the basis for the analysis of slope erosion stability and the slope protection design of the high-speed railway subgrade slope.

A Framework to Identify Rock Glaciers and Model Mountain Permafrost in the Jhelum Basin, Kashmir Himalaya, India

AbstractDeglaciation has led to the transformation of glaciers into rock glaciers in various mountainous regions worldwide. However, the science of permafrost and rock glaciers remains under‐researched in the Himalayan region. This study presents a detailed inventory, dynamics, and permafrost distribution map for the Jhelum basin in the Kashmir Himalaya. The Permafrost Zonation Map (PZM) is created using a Logistic Regression Model based on topographic and climatic variables. High‐resolution satellite images are used to identify rock glaciers as visual indicators. Active and relic rock glaciers are classified based on surface topography and geomorphology. Results reveal 207 rock glaciers in the Jhelum basin, covering ∼50 km2, with over 100 falling into the active category. The PZM aligns well with the global permafrost zonation index map. Slope, aspect, and elevation of rock glaciers are computed using the ASTER Digital Elevation Model. The average elevations range from 3,700 m to 4,550 m, and the average surface slope ranges from 12° to 26°, with maximum slopes from 25° to 65°. Most rock glaciers are oriented toward the south or southeast. Field investigations confirm that these rock glaciers occur in highly elevated regions with steep slopes. This study provides valuable information on the high areal abundance of permafrost in the Himalayan region and suggests increased risks of thawing permafrost due to climate warming in the future. The findings contribute to the understanding of permafrost and rock glaciers, filling knowledge gaps in the Himalayan context.

Characterization of the Fels Landslide (Alaska) Using Combined Terrestrial, Aerial, and Satellite Remote Sensing Data

The characterization of landslides located in remote areas poses significant challenges due to the costs of reaching the sites and the lack of reliable subsurface data to constrain geological interpretations. In this paper, the advantages of combining field and remote sensing techniques to investigate the deformation and stability of rock slopes are demonstrated. The characterization of the Fels landslide, a large, slowly deforming rock slope in central Alaska, is described. Historical aerial imagery is used to highlight the relationship between glacier retreat and developing instability. Airborne laser scanning (ALS) and Structure-from-Motion (SfM) datasets are used to investigate the structural geological setting of the landslide, revealing a good agreement between structural discontinuities at the outcrop and slope scales. The magnitude, plunge, and direction of slope surface displacements and their changes over time are studied using a multi-temporal synthetic aperture radar speckle-tracking (SAR ST) dataset. The analyses show an increase in displacement rates (i.e., an acceleration of the movement) between 2010 and 2020. Significant spatial variations of displacement direction and plunge are noted and correlated with the morphology of the failure surface reconstructed using the vector inclination method (VIM). In particular, steeper displacement vectors were reconstructed in the upper slope, compared to the central part, thus suggesting a change in basal surface morphology, which is largely controlled by rock mass foliation. Through this analytical approach, the Fels landslide is shown to be a slow-moving, compound rockslide, the displacement of which is controlled by structural geological features and promoted by glacier retreat.

Elimination method of sliding blockage effect in discrete element simulation of rolling stone based on discrete fracture network and damping joint model

The particle essence of the discrete element method could prevent the rock block from sliding on the slope surface due to the stress concentration between the convex particles of the sliding block and the slope. To eliminate this sliding blockage effect and simulate more realistic rockfall, slope surface was transformed into a series of successive joints by the discrete fracture network technique, and a damping joint model was developed by adding a normal dashpot and a shear dashpot on the smooth joint model that does not have damping properties. The motion processes of sliding, rolling, and collision were simulated by the proposed method, and the damping and movement performances were investigated. The macroscopic sliding and rolling friction coefficients significantly increase with the microscopic friction coefficient and the shear damping ratio. The normal restitution coefficient of collision decreases with the normal damping ratio, while the shear restitution coefficient of collision decreases with both the shear damping ratio and the friction coefficient. Furthermore, the simulation of a rockfall case demonstrates the proposed method represented a more realistic movement process and more plentiful characteristics of collision, sliding and rolling, compared with the simulated results of Rocfall software.

Control of local topography and surface patterning on the formation and stability of a slope permafrost peatland at 4800-m elevation on the central Qinghai-Tibetan Plateau

Some sloping peatlands in northern regions often develop surface microtopographic patterns to maintain their water balance and ecosystem functioning. However, we do not know whether and how spatial patterning would influence the water balance and peat formation of permafrost-affected peatlands in relatively dry regions. Here we used data from the field observations and Unmanned Aerial Vehicle (UAV) survey of a slope peatland at an elevation of around 4800 m in the hinterland of the Qinghai-Tibetan Plateau (QTP) to document and understand the topographic controls of water balance and vegetation growth. Our terrain analysis result shows that the peatland—located on the middle section of a hillslope—has a gentle slope of 5.6° ± 2.5°, while the non-peatland upper section has a steep slope of 12° ± 4.5°. The great upstream catchment area and the presence of shallow impermeable permafrost likely create a saturated condition for peat formation. Our UAV results show obvious spatial patterning of abundant pools and ridges across this peatland, and pool sizes and ridge abundance increase with increasing slopes, suggesting that slope-controlled water flow gradient is the main driver of ridge formation and that ridges is to slow down the runoff. UAV-derived greenness values show a positive relationship with the total pool extent locally (R2 = 0.60) and decrease with increasing distance from the individual pools, suggesting sensitive responses of vegetation growth to surface moisture. Thus, enhanced vegetation growth and likely resultant great peat accumulation immediately around pools potentially further differentiate surface microtopography, strengthening the pool stability. We conclude that the local slope gradient, surface patterning (pools and ridges) and permafrost interact together to regulate water flow and maintain water balance, which in turn regulate the vegetation growth, peat accumulation and peatland stability. Our study implies that the delicate water balance maintained partly by microtopography is sensitive to climate change—especially potential extreme hydroclimate events—and natural and human-induced disturbances that may modify the surface patterning and weaken the peatland’s stability, affecting the carbon sequestration ability of this type of peatlands.

PRINCIPLES OF CALCULATIONS AND ARRANGEMENT OF LOCAL DRAINAGE SYSTEMS IN PRIVATE BUILDING TERRITORIES

Abnormally heavy rains in the first two spring months of 2023 revealed the unpreparedness and lack of protection of many settlements in the Kyiv region from excessive moisture and inundation. Among them, is Novi Petrivtsi village, where the natural conditions for surface runoff and precipitation infiltration (lack of visible surface slopes and poorly permeable cover sediments) are unfavourable and significantly complicated by buildings, and a network of highways. The long-term retention of water on the surface, the rise of groundwater levels, and the layered structure of the upper part of the geological section provide grounds for the use of combined local drainage systems with compliance with drainage standards of at least 3,0 m. Since the high density of buildings often does not allow for contour drainage around residential buildings, it is necessary to lay single-line horizontal drainage to a greater depth than for a conventional contour drainage of 3,5 meters or more. However, the lack of roadside ditches and other water intakes and means of orderly drainage do not allow homestead drainage systems to work as efficiently as possible. This requires the creation of an orderly system of water intakes (trenches and closed collectors) on the scale of the village. Foreign experience convinces that the rational planning of such systems is possible under the conditions of establishing the character of rainfall distribution with a resolution of 1–5 minutes in time and a step of 500 m across the area. Meteorological radar is used to record radar images of rain and study its intensity. An effective solution to the water drainage problem is impossible without detailed engineering and geological investigations. Due to them, litho-facies inhomogeneities in the aeration zone and water-saturated stratum, which lead to the retention and support of groundwater, were discovered in the local area. Taking into account the spatial boundaries of these engineering and geological elements allow drainage more efficiently. Drainage capacity is substantiated by forecasts of changes in the maximum amount of precipitation per day and two days in a row. Due calculating the drainage capacity, it should be taken into account that the maximum amount of precipitation in the future period will have a guarantee of 0,5-2,0% less than the actual maximum values. In the calculation part, the main attention is paid to the selection of equations for determining the width of influence of a single horizontal drain. Five formulas have been selected that can be used to solve similar problems. The time of onset of the established mode of operation of a single drain was calculated. Future research should focus on the collection of high-resolution rainfall and local urban runoff data, as well as the implementation of urban drainage models.

Morphological analysis of polar landing regions for a solar powered ice drilling mission

Planning of mission toward the lunar polar region is supported here by the analysis and better understanding of the most frequent landforms: craters on the Moon in the polar region between 79.30 and 84.35 southern latitude. This work surveys impact crater morphologies and spatial density based age estimation and slopes for eight earlier selected, large candidate landing regions of the Luna-27 solar powered ice drilling mission at the southern lunar polar region. The morphological, morphometrical, slope and dating analysis provided the following results: The d/D values of craters follow the earlier found d/D trend for larger craters, but there is a scatter in depth values related to the ageing of craters. The occurrence of shallow craters looks to be somewhat more abundant here than at lower lunar latitudes, in agreement with Mahanti et al. (2015). Beside fresh craters, rock boulders also occur at some km sized local topographic elevations, indicating erosion of ∼1 m thick regolith layer by micro-scale impacts roughly on the scale of 100 Ma.Characteristic temporal sequence of change in the morphology of about 100 m-sized craters confirmed earlier results. The sequence starts from the freshest craters, with mass wasting produced stripes in the interior slope, later diminish of high-reflectance proximal ejecta happens, then boulders, and even later elevated rims diminish. The surveyed large terrains showed crater statistics-derived model ages ranged between 3.9 and 4.2 Ga, indicating below a thin pulverised surface regolith layer, the topography of the poorly fragmented bedrock below it still holds the Late Heavy Bombardment aged basement. The equilibrium crater population was possibly identified below the 100–200 m diameter range. Surveying crater retention at >30° slopes indicates exposure of 78–140 Ma for steep terrains, and 330–150 Ma for flat <5° slope surfaces considering the size domain below 100 m diameter. This observation indicates rejuvenation of the top few m thin layer of slopes produces faster mixing than on plains.The surveyed kilometre sized craters formed about 1–2 Ga ago, and show correlation between formation age and depth, indicating an infilling rate around 100 m thickness in 1 Ga duration. This is 2 orders of magnitude larger than the 1–2 m impact driven regolith mixing depth during the same period. Thus, while impact mixing desiccates the shallow top regolith layer, inside km scale craters earlier accumulated ice might still be there shielded by faster rock debris accumulation.The surveyed candidate landing regions were evaluated according to general landing safety, lower temperature (to support ice preservation), and solar illumination (for energy supply). Comparing the eight regions, altogether 5.1% of their total area was found to meet with the threshold values of slope angle below 8°, modelled 1 m deep subsurface temperature below 125 K and at least 20% of time available solar illumination and Earth visibility. The largest continuous area that fulfil the used constraints are present in the candidate LS8 area at −82.70°, −82.72°.

Modelling erosion and stability degradation of a reservoir slope under periodic water level fluctuations

Water level rise and fall can lead to changes in seepage flow in the bank slopes of reservoirs. Cyclic seepage flow can result in the redistribution and even loss of fine particles in the slope, which eventually influences the slope stability. In this study, numerical simulations were conducted based on a multispecies transport finite element method (FEM) to investigate the influence of periodic water level fluctuations on the reservoir bank slope. The unsaturated soil was treated as a five-constituent mixture, by which erosion and deposition behaviours were captured by phase transition between deposited and fluidized fines. A constitutive model for suffusion considering the hydraulic fluctuation effect was employed to quantify the erosion process. The change in the seepage field and the corresponding evolution of the erosion rate and fines eroded ratio in the slope during the fluctuation period were investigated. The influence of the water level fluctuation frequency on the fines redistribution in the slope was analysed. Furthermore, the evolution patterns of the slope stability under different fluctuation frequencies were compared. The numerical results indicated that a higher fluctuation frequency could promote fine particle loss in the zones near the slope surface, consequently inducing greater deterioration in the slope stability.

A New Reflected Target Optical Assessment System

NREL has completed stage 1 development of an indoor optical measurement tool for fully assembled heliostats and single facets. This tool began as an indoor version of NREL’s outdoor Non-Intrusive Optical (NIO) measurement technique [1]. It uses similar techniques to other available tools (deflectometry, photogrammetry, etc.), but is designed to require very little infrastructure, labor, and time to set up and collect surface slope and canting measurements, making it a valuable tool for quality assurance and laboratory measurement of heliostat optics. It accomplishes this by using computer vision, photogrammetry, and multiple images stitched together to minimize the printed target size and required setup precision. This adaptable setup is useful for taking measurements at a variety of heliostat pointing angles, and for measuring fully assembled heliostats on the assembly line. In this paper, we describe the methodology behind the measurement system, present an initial analysis of its uncertainty and sensitivity, and compare it with established optical measurement systems.

Flow field analysis and particle erosion of tunnel‐slope systems under coupling between runoff and fast (slow) seepage

AbstractThe presence of particles on the surface of a tunnel slope renders it susceptible to erosion by water flow, which is a major cause of soil and water loss. In this study, a nonlinear mathematical model and a mechanical equilibrium model are developed to investigate the distribution of flow fields and particle motion characteristics of tunnel slopes, respectively. The mathematical model of flow fields comprises three parts: a runoff region, a highly permeable soil layer, and a weakly permeable soil layer. The Navier‒Stokes equation controls fluid motion in the runoff region, while the Brinkman‐extended Darcy equation governs fast and slow seepage in the highly and weakly permeable soil layers, respectively. Analytical solutions are derived for the velocity profile and shear stress expression of the model flow field under the boundary condition of continuous transition of velocity and stress at the fluid‒solid interface. The shear stress distribution shows that the shear stress at the tunnel‐slope surface is the largest, followed by the shear stress of the soil interface, indicating that particles in these two locations are most vulnerable to erosion. A mechanical equilibrium model of sliding and rolling of single particles is established at the fluid‒solid interface, and the safety factor of particle motion (sliding and rolling) is derived. Sensitivity analysis shows that by increasing the runoff depth, slope angle, and soil permeability, the erosion of soil particles will be aggravated on the tunnel‐slope surface, but by increasing the particle diameter, particle‐specific gravity, and particle stacking angle, the erosion resistance ability of the tunnel‐slope surface particles will be enhanced. This study can serve as a reference for the analysis of surface soil and water loss in tunnel‐slope systems.

Indexing and segment-level mapping of soil quality in a spatially complex watershed in northern Iran.

Soil quality (SQ) modeling and mapping is a leading research field aiming to provide reproducible and cost-effective yet accurate SQ predictions at the landscape level. This endeavor was conducted in a complex watershed in northern Iran. We classified the region into spectrally and topographically homogenous land units (average area of 48 ± 23ha) using object-based segmentation analysis. Following the physicochemical analysis of soil samples from 98 stations, the Nemoro soil quality index (SQIn) was produced using the minimum dataset procedure and a non-linear sigmoid scoring function. SQIn values averaged 0.21 ± 0.06 and differed statistically between major land uses. To predict and map SQIn for each land unit, the best-performing regression model (F(3, 84) = 45.57, p = 0.00, R2 = 0.62) was built based on the positive contribution of the mean Landsat 8-OLI band 5, and negative influence of land surface temperature retrieved from Landsat 8-OLI band 10 and surface slope (t-test p-values < 0.01). Results showed that dense-canopy woodlands located in low-slope land units exhibit higher SQIn while regions characterized by either low-vegetation or steep-sloped land units had SQ deficits. This study provides insights into SQ prediction and mapping across spatially complex large-scale landscapes.

Marginal Distribution Fitting Method for Modelling Flood Extremes on a River Network

This study utilized a max-stable process (MSP) model with a dependence structure defined via a non-Euclidean distance metric, with the goal of modelling extreme flood data on a river network. The dataset was composed of mean daily discharge observations from 22 United States Geological Survey streamflow gaging stations for river basins in Missouri and Arkansas. The analysis included the application of the elastic-net penalty to automatically build spatially varying trend surfaces to model the marginal distributions. The dependence model accounted for the river distance between hydrologically connected gaging sites and the hydrologic distance, defined as the Euclidean distance between the centers of site’s associated drainage areas, for all stations. Modelling the marginal distributions and spatial dependence among the extremes are two key components for spatially modelling extremes. Among the 16 covariates evaluated for marginal fitting, 7 were selected to spatially model the generalized extreme value (GEV) location parameter (for each gaging station’s contributing drainage basin, its outlet elevation, centroid x coordinate, centroid elevation, area, average basin width, elevation range, and median land surface slope). The three covariates selected for the GEV scale parameter included the area, average basin width, and median land surface slope. The GEV shape parameter was assumed to be constant throughout the entire study area. Comparisons of estimates obtained from the spatial covariate model with their corresponding “at-site” estimates resulted in computed values of 0.95, 0.95, 0.94 and 0.85, 0.84, 0.90 for the coefficient of determination, Nash–Sutcliffe efficiency, and Kling–Gupta efficiency for the GEV location and scale parameters, respectively. Brown–Resnick MSP models were fit to independent multivariate events extracted from a set of common discharge data, transformed to unit Fréchet margins while considering different permutations of the non-Euclidean dependence model. Each of the fitted model’s log-likelihood values indicated improved fits when using hydrologic distance rather than Euclidean distance. They also demonstrated that accounting for flow-connected dependence and anisotropy further improved model fit. In this study, the results from both parts were illustrative; however, further research with larger datasets and more heterogeneous systems is recommended.

Effect of excitation frequency and joint density on the dynamic amplification effect of slope surface on jointed rock slopes

This paper presents the slope dynamic response of jointed rock slopes containing three groups of typical joints and analyzes the effect of input harmonic frequency and joint density on the peak horizontal acceleration (PGA) of the slope surface under vertically impinging SV wave (shear vertical wave) excitation. First, the dynamic response of the slope surface of the bedding slope was investigated with a large-scale shaking table test, and the reliability of the numerical model was verified by the physical modeling. Then, a series of jointed rock slope models with different joint densities were established based on the three-dimensional discrete element software 3DEC. It is found that the natural frequency fn of the jointed slope decreases with the increase of joint density. The effect of excitation frequency f on the slope surface dynamic response of the jointed slope is stronger than that of joint density. The closer the f is to the fn, the stronger the slope surface and slope crest dynamic response is. Notably, taking fn as the critical value of f, the slope surface dynamic amplification mode of jointed slope can be divided into two types: when f ≤ fn, the acceleration amplification factor of X-direction (AAF-X) of the slope surface amplifies monotonically with increasing elevation; when f >fn, the AAF-X of the slope surface shows a fluctuated amplification pattern with the increase of elevation. The results of this paper show that in the seismic design of slope engineering, the influence of site conditions on the frequency spectrum characteristics of ground motion should be considered, and then the optimal design should be carried out.

Radar internal reflection horizons from multisystem data reflect ice dynamic and surface accumulation history along the Princess Ragnhild Coast, Dronning Maud Land, East Antarctica

Abstract Ice shelves, which regulate ice flow from the Antarctic ice sheet towards the ocean, are shaped by spatiotemporal patterns of surface accumulation, surface/basal melt and ice dynamics. Therefore, an ice dynamic and accumulation history are imprinted in the internal ice stratigraphy, which can be imaged by radar in the form of internal reflection horizons (IRHs). Here, IRHs were derived from radar data combined across radar platforms (airborne and ground-based) in coastal eastern Dronning Maud Land (East Antarctica), comprising three ice rises and adjacent two ice shelves. To facilitate interpretation of dominant spatiotemporal patterns of processes shaping the local IRH geometry, traced IRHs are classified into three different types (laterally continuous, discontinuous or absent/IRH-free). Near-surface laterally continuous IRHs reveal local accumulation patterns, reflecting the mean easterly wind direction, and correlate with surface slopes. Areas of current and past increased ice flow and internal deformation are marked by discontinuous or IRH-free zones, and can inform about paleo ice-stream dynamics. The established IRH datasets extend continent-wide mapping efforts of IRHs to an important and climatically sensitive ice marginal region of Antarctica and are ready for integration into ice-flow models to improve predictions of Antarctic ice drainage.

Tunnel entrance crossing spoil heap deformations control by micropile combine with coupling beams

Aiming at the deformation control problem of the tunnel entrance crossing the spoil heap at the Xialao junction, this paper adopts the micropile combined with the coupling beams method to treat the spoiled layers. The results show that the excavation of the tunnel after the construction of the micropile and coupling beam will cause vertical deformation of the tunnel and the slope surface. The main reason is that the soil layer structure is loose, and the tunnel excavation causes the whole displacement of the loose body. In addition, the buried depth of the tunnel is shallow, so it cannot form an effective soil arch. The stability process after the construction of the micropile method is the process of stress redistribution, and the rock and soil are gradually compressed and compacted. That is, the construction by the micropile method changes the surrounding rock level of the tunnel and reduces the height of the soil arch. Therefore, it is suggested that the tunnel excavation should be carried out when the micropile is constructed after the soil layers are consolidated completely. The micropile method treats the loose spoiled soil at the tunnel entrance, which saves 73% of the total cost compared with the scheme of directly digging out the accumulation, and the economic benefit is very obvious.

Numerical analysis of liquid sodium spreading on sloped floor surface under pool fire scenario in SFR systems

The accidental leaks of coolant from the heat transport circuit of Sodium-cooled Fast Reactor (SFR) can create fire events due to the reactivity of sodium with atmospheric oxygen, which can pose threat to safe operation of the reactor. The leaked sodium eventually reaches the cell floor, spreads gradually, and forms a burning pool. The thermal consequences of pool fire depend on its surface area, which is determined by the spreading process of sodium on the floor surface. In this context, numerical investigation has been carried out on the spreading behavior of burning sodium pool on the plane/sloped cell floor by developing a 3-D numerical model based on the viscous-gravity current equation of the shallow layer model. The governing equations of the model have been solved numerically by implementing the Finite Volume Method. The model developed has been validated using the experimental results published on liquid pool spreading under burning and non-burning conditions on plane and sloped floors for different leak rates. Using this model, numerical simulations have been carried out on sodium pool spreading under various leak scenarios envisaged in SFR cells based on the specific burning characteristics of sodium pool fire. The time-varying pool size and shape, pool height profile, and maximum pool area have been estimated for a wide range of sodium leak rates and typical floor slopes of interest to nuclear power plants. These predictions contribute towards the numerical evaluation of sodium pool fire scenarios pertaining to the safety of SFR.