Experimental comparison of the lateral resistance of tracks with steel slag ballast and limestone ballast materials

2016 ◽  
Vol 231 (2) ◽  
pp. 175-184 ◽  
Author(s):  
Morteza Esmaeili ◽  
Reza Nouri ◽  
Kaveh Yousefian
Keyword(s):  
Field Experiments ◽  
Steel Slag ◽  
Railway Track ◽  
Experimental Comparison ◽  
Lateral Stability ◽  
Railway Ballast ◽  
Long Distance ◽  
Expansion Joints ◽  
Lateral Resistance ◽  
Weak Points

Extending the use of continuous welded rails by eliminating the weak points (expansion joints) of a railway track especially in sharp curves, which has resulted in increasing the operational speed and axle load of rolling stocks, enhances the special attention to the issue of track lateral resistance. In this regard, the ballast layer interaction with sleepers plays a crucial role in providing the track lateral stability. In many railway projects supplying the appropriate ballast materials has encountered serious restrictions owing to the lack of qualified ore and also their long distance to the project’s site. With the development of steel industry, the quantity of production and accumulation of steel slag as a waste material has increased. In recent years, a great deal of attention has been paid to the use of this material as railway ballast. According to the physical and mechanical characteristics of steel slags, such as high specific gravity and the granular roughness respect to the limestone ballast, the usage of slag ballast can improve the track lateral stability. In this research, many field experiments were conducted on tracks with steel slag ballast and limestone ballast materials considering the same gradation. In this matter, several single tie push tests were carried out on both tracks with various ballast geometries. The ballast depth was considered as 30, 40, and 50 cm and the shoulder ballast width was equal to 30 and 40 cm. Moreover, the shoulder ballast height was chosen 0 and 10 cm. Consequently, the lateral resistance of both tracks was measured and compared in the same conditions. In overall, the obtained results confirmed a 27% increase in lateral resistance of track with steel slag ballast respect to that with limestone ballast.

scholarly journals Development of fragility curves for railway ballast and embankment scour due to overtopping flood flow

2016 ◽  
Author(s):  
Ryota Tsubaki ◽  
Koji Ichii ◽  
Jeremy D. Bricker ◽  
Yoshihisa Kawahara
Keyword(s):  
Spatial Distribution ◽  
Failure Probability ◽  
Fragility Curves ◽  
Railway Track ◽  
Single Track ◽  
Hydraulic Analysis ◽  
Railway Ballast ◽  
Log Normal ◽  
Flood Flow

Abstract. Fragility curves evaluating risk of railway track ballast and embankment fill scour were developed. To develop fragility curves, two well-documented single-track railway washouts during two recent floods in Japan were investigated. Type of damage to the railway was categorized into no damage, ballast scour, and embankment scour, in order of damage severity. Railway overtopping surcharge for each event was estimated via hydrologic and hydraulic analysis. Normal and log-normal fragility curves were developed based on failure probability derived from field records. A combined ballast and embankment scour model was validated by comparing the spatial distribution of railway scour with the field damage record.

scholarly journals Micro-mechanical investigation of railway ballast behavior under cyclic loading in a box test using DEM: effects of elastic layers and ballast types

2019 ◽  
Vol 21 (4) ◽  
Author(s):  
Nishant Kumar ◽  
Bettina Suhr ◽  
Stefan Marschnig ◽  
Peter Dietmaier ◽  
Christof Marte ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Early Stage ◽  
Damage Model ◽  
Simulation Models ◽  
Railway Track ◽  
Maintenance Cost ◽  
Particle Movement ◽  
Railway Ballast ◽  
Elastic Layers ◽  
The Impact

Abstract Ballasted tracks are the commonly used railway track systems with constant demands for reducing maintenance cost and improved performance. Elastic layers are increasingly used for improving ballasted tracks. In order to better understand the effects of elastic layers, physical understanding at the ballast particle level is crucial. Here, discrete element method (DEM) is used to investigate the effects of elastic layers – under sleeper pad ($$\text {USP}$$USP) at the sleeper/ballast interface and under ballast mat ($$\text {UBM}$$UBM) at the ballast/bottom interface – on micro-mechanical behavior of railway ballast. In the DEM model, the Conical Damage Model (CDM) is used for contact modelling. This model was calibrated in Suhr et al. (Granul Matter 20(4):70, 2018) for the simulation of two different types of ballast. The CDM model accounts for particle edge breakage, which is an important phenomenon especially at the early stage of a tamping cycle, and thus essential, when investigating the impact of elastic layers in the ballast bed. DEM results confirm that during cyclic loading, $$\text {USP}$$USP reduces the edge breakage at the sleeper/ballast interface. On the other hand, $$\text {UBM}$$UBM shows higher particle movement throughout the ballast bed. Both the edge breakage and particle movement in the ballast bed are found to influence the sleeper settlement. Micro-mechanical investigations show that the force chain in deeper regions of the ballast bed is less affected by $$\text {USP}$$USP for the two types of ballast. Conversely, dense lateral forces near to the box bottom were seen with $$\text {UBM}$$UBM. The findings are in good (qualitative) agreement with the experimental observations. Thus, DEM simulations can aid to better understand the micro-macro phenomena for railway ballast. This can help to improve the track components and track design based on simulation models taking into account the physical behavior of ballast. Graphical Abstract

Colonization of depopulated crinoids by symbionts: who comes from the bottom and who from the water column?

2015 ◽  
Vol 95 (8) ◽  
pp. 1607-1612 ◽  
Author(s):  
E.S. Mekhova ◽  
P.Y. Dgebuadze ◽  
V.N. Mikheev ◽  
T.A. Britayev
Keyword(s):  
Water Column ◽  
Field Experiments ◽  
Dispersal Ability ◽  
Long Distance ◽  
Sandy Substrate ◽  
Limited Dispersal ◽  
Set Up ◽  
Almost All ◽  
High Degree

Previous experiments with the comatulid Himerometra robustipinna (Carpenter, 1881) demonstrated intensive host-to-host migration processes for almost all symbiotic species both within host aggregations and among hosts separated by several metres. The aim of this study was to check the ability of symbionts to complete long-distance migrations, by means of two in situ experiments which depopulated the crinoid host. Two different sets of field experiments were set up: exposure of depopulated crinoids (set 1) on stony ‘islands’ isolated from native crinoid assemblages by sandy substrate, and (set 2) in cages suspended in the water column. Hosts from set 1 were exposed for 1, 2, 3 and 4 weeks to assess whether substrate has an influence on the symbionts' long-distance migrations. In set 2 cages were exposed for 10–11 days, aiming to check whether symbionts were able to disperse through the water column with currents. These experiments allow the conclusion that post-settled symbionts can actively migrate among their hosts. Symbionts are able to reach their hosts by employing two different ‘transport corridors’, by drifting or swimming in water column, and by moving on the bottom. Comparison of experimental results allows the division of symbionts into two conventional groups according to the dispersal ability of their post-settled stages: (1) species able to complete long-distance migrations, (2) species unable to migrate or having limited dispersal ability. The finding of the free-living shrimp Periclimenes diversipes Kemp, 1922 in set 2 raises the question about the factors that affect such a high degree of specialization of crinoid assemblages.

Experimental and Numerical Study of Railway Ballast Compactness during Tamping Process

2013 ◽  
Vol 690-693 ◽  
pp. 2730-2733
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bo Yan ◽  
Jun Feng Sun
Keyword(s):  
Discrete Element Method ◽  
Numerical Study ◽  
Discrete Element ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Before And After ◽  
Filling Method ◽  
Element Method

Railway ballast tamping operations is employed in order to restore the geometry of railway track distorted by train traffics. The main goal is to compact the stone ballast under the sleepers supporting the railway squeezing and vibrations. The ballast compactness is the most direct index for evaluating the effect of tamping operation. This paper presents an experimental method used to detect the railway ballast compactness before and after tamping operation based on water-filling method, and creates a discrete element analysis model of railway ballast which analyzes the change of ballast compactness before and after tamping operation based on discrete element method. The simulation results are very similar with experimental results, which verify that the discrete element method is an effective method to evaluate the change of railway ballast compactness during tamping process.

Round goby movement patterns in a non-navigable river

2020 ◽  
Vol 77 (3) ◽  
pp. 475-483
Author(s):  
Luděk Šlapanský ◽  
Michal Janáč ◽  
Kevin Roche ◽  
Pavel Jurajda
Keyword(s):  
Native Species ◽  
Field Experiments ◽  
Round Goby ◽  
Neogobius Melanostomus ◽  
Species Dispersal ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Movement Rates ◽  
Established Population ◽  
Future Management

Understanding non-native species dispersal is vital for their future management. The round goby (Neogobius melanostomus) has greatly extended its range since the 1990s, with commercial shipping being the main vector. However, our knowledge regarding their secondary dispersal from points of introduction is surprisingly limited. In this study, a series of field experiments were undertaken on a mid-sized river to assess goby dispersal patterns within an established population, following a simulated release of a large number of propagules, or at a simulated invasion front. Most of the established population remained stationary and just a few individuals undertook long-distance dispersal (principally upstream). Mean distance travelled was 1.1 m·day−1 (max. 29.6 m·day−1). While site fidelity appeared to last for most of the year (including winter), it was surprisingly relaxed during the spawning season. Concentrated release of a large number of propagules resulted in appreciably greater movement rates than in the established population, with upstream movement again dominating. In general, smaller, mostly male fish tended to move further and appeared as first colonizers in uninvaded areas.

Effect of High Temperature Process on Microstructure and Properties of Industrial Steel Slag Cement

2019 ◽  
Vol 814 ◽  
pp. 413-418
Author(s):  
Fang Wang ◽  
Ming Han Xu ◽  
Rui Hua Wang ◽  
Chao Yang ◽  
Ai Xia Chen ◽  
...  
Keyword(s):  
Steel Industry ◽  
High Performance ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Steel Slag ◽  
Holding Time ◽  
Raw Material ◽  
Experimental Comparison ◽  
Slag Cement ◽  
Actual Performance

The construction industry continues to develop and the requirements for cement performance are getting higher and higher. At the same time, in the steel industry, the discharge of steel slag is also increasing. The effective reuse of steel slag has become a prominent problem in the steel industry. . Therefore, it is envisaged to use steel slag as a raw material for the cement production process to produce cement and to produce high-performance cement. The main raw materials of this experiment are steel slag, limestone, sandstone and shale. Through the cement preparation process, the cement is made, and then the cement is made into concrete to test its performance. This experiment mainly studies the sintering temperature and holding time variable. In the experimental test, the analysis and comparison were carried out in five aspects of the degree of macroscopic cracking, particle size, density, microstructure and composition. In the comparison experiment of sintering temperature, with the increase of temperature, the flexural and compressive properties of cement gradually increased. In this test, 1200 °C is the most suitable temperature for the performance of the cement. Through the experimental comparison of different holding time, it is known that with the prolonging of the holding time, the microstructure and actual performance of the cement are continuously enhanced. Comprehensive consideration: the ratio of steel slag in cement ratio is 10%, sintering temperature is 1200 °C, and heat preservation is 2h. The steel slag cement prepared under this condition has the strongest performance.

scholarly journals Particle motion on burned and vegetated hillslopes

2020 ◽  
Vol 117 (41) ◽  
pp. 25335-25343
Author(s):  
Danica L. Roth ◽  
Tyler H. Doane ◽  
Joshua J. Roering ◽  
David J. Furbish ◽  
Aaron Zettler-Mann
Keyword(s):  
Sediment Transport ◽  
Particle Motion ◽  
Debris Flows ◽  
Field Experiments ◽  
Transport Theory ◽  
Surface Characteristics ◽  
Model Parameters ◽  
Mathematical Framework ◽  
Long Distance ◽  
Heavy Tailed

Climate change is causing increasingly widespread, frequent, and intense wildfires across the western United States. Many geomorphic effects of wildfire are relatively well studied, yet sediment transport models remain unable to account for the rapid transport of sediment released from behind incinerated vegetation, which can fuel catastrophic debris flows. This oversight reflects the fundamental inability of local, continuum-based models to capture the long-distance particle motions characteristic of steeplands. Probabilistic, particle-based nonlocal models may address this deficiency, but empirical data are needed to constrain their representation of particle motion in real landscapes. Here we present data from field experiments validating a generalized Lomax model for particle travel distance distributions. The model parameters provide a physically intuitive mathematical framework for describing the transition from light- to heavy-tailed distributions along a continuum of behavior as particle size increases and slopes get steeper and/or smoother. We show that burned slopes are measurably smoother than vegetated slopes, leading to 1) lower rates of experimental particle disentrainment and 2) runaway motion that produces the heavy-tailed travel distances often associated with nonlocal transport. Our results reveal that surface roughness is a key control on steepland sediment transport, particularly after wildfire when smoother surfaces may result in the preferential delivery of coarse material to channel networks that initiate debris flows. By providing a first-order framework relating the statistics of particle motion to measurable surface characteristics, the Lomax model both advances the development of nonlocal sediment transport theory and reveals insights on hillslope transport mechanics.

scholarly journals Beyond species recognition: somatic state affects long-distance sex pheromone communication

2015 ◽  
Vol 282 (1812) ◽  
pp. 20150832 ◽  
Author(s):  
Johanna Chemnitz ◽  
Petra C. Jentschke ◽  
Manfred Ayasse ◽  
Sandra Steiger
Keyword(s):  
Body Size ◽  
Sex Pheromone ◽  
Long Range ◽  
Sex Pheromones ◽  
Field Experiments ◽  
Species Recognition ◽  
Long Distance ◽  
Central Processing ◽  
Pheromone Emission ◽  
Somatic State

Long-range sex pheromones have been subjected to substantial research with a particular focus on their biosynthesis, peripheral perception, central processing and the resulting orientation behaviour of perceivers. Fundamental to the research on sex attractants was the assumption that they primarily coordinate species recognition. However, especially when they are produced by the less limiting sex (usually males), the evolution of heightened condition dependence might be expected and long-range sex pheromones might, therefore, also inform about a signaller's quality. Here we provide, to our knowledge, the first comprehensive study of the role of a male's long-range pheromone in mate choice that combines chemical analyses, video observations and field experiments with a multifactorial manipulation of males' condition. We show that the emission of the long-distance sex pheromone of the burying beetle, Nicrophorus vespilloides is highly condition-dependent and reliably reflects nutritional state, age, body size and parasite load—key components of an individual's somatic state. Both, the quantity and ratio of the pheromone components were affected but the time invested in pheromone emission was largely unaffected by a male's condition. Moreover, the variation in pheromone emission caused by the variation in condition had a strong effect on the attractiveness of males in the field, with males in better nutritional condition, of older age, larger body size and bearing less parasites being more attractive. That a single pheromone is influenced by so many aspects of the somatic state and causes such variation in a male's attractiveness under field conditions was hitherto unknown and highlights the need to integrate indicator models of sexual selection into pheromone research.

scholarly journals Field Investigations on the Effects of Track Lateral Supports on the Ballasted Railway Lateral Resistance

2020 ◽  
Author(s):  
Jabbar Ali Zakeri ◽  
Milad Alizadeh Galdiani ◽  
Seyed Ali Mosayebi
Keyword(s):  
Numerical Modeling ◽  
Bilinear Form ◽  
Field Tests ◽  
New Method ◽  
Railway Track ◽  
Lateral Forces ◽  
Lateral Resistance ◽  
Field Investigations ◽  
Continuous Welded Rail ◽  
Lateral Displacements

Lateral movements of the ballasted railway track especially in the continuous welded rail (CWR) occur in sharp curves because of high lateral forces. Several strategies have been proposed to increase the track lateral resistance which most of them related to track curves with small radii. In this paper, track lateral supports as a new method have been utilized and a series of field tests have been conducted by using the Single Tie Push Tests (STPT) and Multi Tie Push Tests (MTPT) and their results are compared with the numerical modeling. The results of numerical modeling and field tests show that the track lateral resistance significantly increases in the railway with lateral supports, so that the lateral displacements of track are as a bilinear form.

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