A new field investigation on the lateral and longitudinal resistance of ballasted track

2018 ◽  
Vol 232 (8) ◽  
pp. 2138-2148 ◽  
Author(s):  
Saeed Mohammadzadeh ◽  
Morteza Esmaeili ◽  
Fatemeh Khatibi
Keyword(s):  
Field Study ◽  
Field Investigation ◽  
Test Track ◽  
Lateral Resistance ◽  
Longitudinal Stiffness ◽  
Wide Range ◽  
Ballasted Track ◽  
Good Consistency ◽  
Southwest Region ◽  
Longitudinal Resistance

Track buckling is a complicated phenomenon that is caused by a wide range of parameters including the nature of track loading and the lateral and longitudinal resistance of a track. In this paper, the results of a field study on a test track in the Aprin railway station (in the southwest region of Tehran city) are presented to investigate the lateral and longitudinal resistance of the ballasted track. The lateral resistance of the track is measured by using both the single tie (sleeper) push test and the sleeper lateral pull test, and the results of the two methods are found to be compatible. The contributions of the ballast shoulder, crib, and the base part in the total lateral resistance are obtained for the loose and compacted ballast conditions, which showed good consistency with the presented data of literature. The longitudinal resistance is measured by using an innovative setup prepared on the test track. The measured longitudinal stiffness per sleeper is approximately twice of what was measured in the previous studies on track panels. The measured longitudinal stiffness during the unloading process is found to be 40% of the loading stiffness.

scholarly journals Research on the longitudinal mechanical behaviours of subway turnouts of large slope under train braking force

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110283
Author(s):  
Zhiping Zeng ◽  
Ji Hu ◽  
Chunyu Tian ◽  
Ping Li ◽  
Xiangdong Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Change ◽  
Mechanical Characteristics ◽  
Element Model ◽  
Longitudinal Displacement ◽  
Longitudinal Deformation ◽  
Longitudinal Stiffness ◽  
Mechanical Behaviours ◽  
Longitudinal Resistance ◽  
Safety And Stability

To study subway turnouts’ adaptability to steep gradients, a finite element model of a metro No. 9 simple turnout was established. The main works include: (1) The train’s most unfavourable loading condition was modelled. (2) The turnout’s longitudinal displacement and stress were analysed with different gradients under the train braking load, temperature change load and a combination of the two, to determine the structure’s safety and stability under the most unfavourable working conditions. (3) The turnout structure’s cumulative longitudinal deformation under reciprocating load was studied. Both a fastener longitudinal resistance-displacement experiment under reciprocating load and a numerical simulation of No. 9 turnout modelled by the finite element modelling software, ANSYS, were carried out to study the gradient’s influence on the turnout’s longitudinal mechanical characteristics. (1) The turnout’s longitudinal displacement and stress increase linearly with an increase in gradient and temperature change, both of which are unfavourable to the turnout structure. As the gradient increases from 0‰ to 30‰, the longitudinal stress and displacement increase by more than 10%. (2) The turnout’s rail strength and displacement on a 30‰ slope under the most unfavourable load conditions are within the specification limitations. (3) Under reciprocating load, the fastener longitudinal stiffness decreases and the maximum and residual longitudinal displacement of the switch rail increase; an increased gradient intensifies these effects on the turnout.

scholarly journals Ballast bed resistance characteristics based on discrete-element modeling

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878146 ◽  
Author(s):  
Zhiping Zeng ◽  
Shanyi Song ◽  
Weidong Wang ◽  
Haijian Yan ◽  
Guoshu Wang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Discrete Element ◽  
Discrete Element Modeling ◽  
Slope Gradient ◽  
Three Dimensional Model ◽  
Lateral Resistance ◽  
In Situ Experiments ◽  
Distribution Limits ◽  
Longitudinal Resistance

In this study, in situ experiments were conducted to study the changing characteristics of the lateral and longitudinal resistance of a ballast bed, and a three-dimensional model for the ballast bed and sleeper was constructed based on the discrete-element method. The effects of the lateral and longitudinal resistance of the ballast bed, such as gravel ballast grading, sleeper depth, the angle of the shoulder slope, and ballast bed shoulder width, among others, were studied. The results suggest that (1) the lateral and longitudinal resistance of the ballast bed increases with the widening of ballast grading, and within the size distribution limits, the resistance of the ballast bed satisfies the specification; (2) the lateral and longitudinal resistance of ballast bed increases with an increase in the sleeper depth and the resistance of ballast bed satisfies the specifications for sleeper depth greater than 150 mm; (3) the lateral resistance of the ballast bed increases with a decrease in the angle of the shoulder slope, whereas the longitudinal resistance remains unchanged and the resistance of the ballast bed satisfies the specifications for slope gradient of 1:1.75 or less; and finally, (4) the lateral resistance of the ballast bed increases with the widening of the ballast bed shoulder, whereas the longitudinal resistance remains unchanged, and the resistance of ballast bed satisfies the specifications when the shoulder width is greater than 400 mm.

scholarly journals Stilbenes in the different organs of Vitis vinifera cv. Merlot grafted on Teleki Kober 5BB rootstock

OENO One ◽  
2017 ◽  
Vol 51 (3) ◽  
pp. 323 ◽  
Author(s):  
Gyöngyi Németh ◽  
Orsolya Hegyi ◽  
Attila Dunai ◽  
Laszlo Kocsis
Keyword(s):  
Vitis Vinifera ◽  
Field Study ◽  
Primary Source ◽  
Dry Weight ◽  
Shoot Tips ◽  
Font Size ◽  
Plant Organs ◽  
Wide Range ◽  
Berry Skins ◽  
Winter Buds

<p style="text-align: justify;"><span style="font-size: medium;"><strong>Aim: </strong>To determine which of the grapevine organ is the richest in stilbene, like the t-piceid, t-resveratrol and ε-viniferin and would it be useful as by-product of viticulture for processing stilbene concentrate.</span></p><p style="text-align: justify;"><span style="font-size: medium;"><strong>Methods and results: </strong>Nine organs, such as cane, buds, shoot tips, inflorescences, clusters at veraison, matured berry skins, seeds and cluster stems, of Merlot grafted on Teleki Kober 5BB rootstock were collected during a year and its ethanolic extractions were analyzed via HPLC-FLD. Stilbene content of the different organs occurred in a wide range, the lowest was 3.15 mg/kg dry weight (dw) measured in the seeds and the highest 2265 mg/kg dw in the buds.</span></p><p style="text-align: justify;"><span style="font-size: medium;"><strong>Conclusion:</strong> The present research demonstrated that different grapevine organs contain different amount of stilbene in the vineyard. The winter-buds, the roots and the matured cane internodes of Merlot are significantly richer in t-resveratrol and t-ε-viniferin than the green vegetative and generative parts we examined in one growing year. </span></p><p style="text-align: justify;"><span style="font-size: medium;"><strong>Significance and impact of the study: </strong>According to our knowledge there was no stilbenes measuring in several plant organs of a vine cultivar in field study, in vineyard. Our research pointed out the pruned cane could be primary source of stilbene of the health-industry. Beside that grape root is a by-product of grapevine nursery is also rich in stilbene. </span></p>

Investigating Taylor’s frozen turbulence hypothesis in the surface layer at an ideal desert field site using fibre-optic distributed temperature sensing

2021 ◽  
Author(s):  
Rainer Hilland ◽  
Andreas Christen ◽  
Roland Vogt
Keyword(s):  
Boundary Layer ◽  
Sonic Anemometer ◽  
Field Work ◽  
Field Investigation ◽  
Temperature Sensing ◽  
Temperature Fields ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Plan View ◽  
Wide Range

&lt;p&gt;Taylor&amp;#8217;s frozen turbulence hypothesis is the most critical assumption through which time-resolving sensors may be used to derive statistics of the turbulent spatial field. Namely, it relates temporal autocorrelation to spatial correlation via the mean wind speed and is invoked in almost all boundary layer field work. Nevertheless, the conditions and scales over which Taylor&amp;#8217;s hypothesis is valid remain poorly understood in the atmospheric boundary layer.&lt;/p&gt; &lt;p&gt;As part of the Namib Turbulence Experiment (NamTEX) campaign in March 2020, a pseudo-3D fibre-optic distributed temperature sensing (DTS) array was installed within a 300 x 300 m area in the Namib desert. The array is X-shaped in plan view and contains 16 measurement heights from 0.45 m to 2.85 m. Fibre-optic sensing provides air temperature measurements at unprecedented spatio-temporal density (0.25 m horizontally, 0.17 m vertically, and 1 Hz) and was coupled with a vertical array of traditional sonic anemometer point measurements to investigate the relationship between spatial and temporal temperature fields. The Namib provides an ideal location for fundamental boundary layer research: homogenous flat surfaces, no vegetation, little moisture, strong solar forcing, regular and repeated clear-sky conditions, and a wide range of atmospheric stabilities.&lt;/p&gt; &lt;p&gt;Using the NamTEX DTS array we present the first field investigation of Taylor&amp;#8217;s hypothesis that considers boundary layer stability and is independent of wind direction. A novel method of 2d horizontal cross-correlation between all possible points of a single height of the DTS is employed to produce spatial &amp;#8216;maps&amp;#8217; of the turbulent flow, whose velocity, direction, and size may be tracked through time.&lt;/p&gt;

Suggestion for allowable additional compressive stress based on track conditions

2017 ◽  
Vol 232 (5) ◽  
pp. 1309-1325 ◽  
Author(s):  
Kyung-Min Yun ◽  
Beom-Ho Park ◽  
Hyun-Ung Bae ◽  
Nam-Hyoung Lim
Keyword(s):  
Compressive Stress ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Additional Stress ◽  
Analysis Model ◽  
Temperature Changes ◽  
Lateral Resistance ◽  
Ballasted Track ◽  
Continuous Welded Rail ◽  
Track Bridge

A continuous welded rail has immovable zones due to its structural characteristics. In an immovable zone, thermal expansion and contraction of rails are restricted when the temperature changes, thereby causing excessive axial force on the rail. When the immovable zone of the continuous welded rail is located on a bridge, additional stress and displacement occur through track–bridge interactions. Additional stress and displacement of the rail compared to the embankment area are restricted when constructing the bridge under the continuous welded rail track to prevent problems with the track–bridge interaction according to UIC 774-3R and Euro codes. According to the various codes, the maximum allowable additional compressive stress is 72 MPa, with the conditions of a curve with a radius (R) ≥ 1500 m, UIC 60 continuous welded rail (tensile strength of at least 900 MPa), ballasted track with concrete sleepers and 30 cm of deep for a well-consolidated ballast. However, the lateral resistance that has the greatest effect on track stability can depend on the conditions mentioned above. Therefore, an additional review of various track conditions is required. In this paper, an evaluation of the current criteria was performed using the minimum buckling strength calculation formula, and the allowable additional stress on the rail suggested by codes could only be used on tracks with a large lateral resistance above 18 kN/m/track. Thus, a three-dimensional nonlinear analysis model was developed and analyzed to calculate the allowable additional compressive stress considering various track conditions. According to the results of the analysis, the allowable additional compressive stress was reduced with a comparatively small lateral resistance. The freedom of design can be enhanced with respect to the parameters of various track and bridge conditions using this model.

Thermal relations of the malle fragon Amphibolurus fordi (Lacertilia : Agamidae)

1974 ◽  
Vol 22 (3) ◽  
pp. 319 ◽  
Author(s):  
HG Cogger
Keyword(s):  
Body Temperature ◽  
Field Study ◽  
New South ◽  
Close Association ◽  
The Body ◽  
Total Effect ◽  
Body Temperatures ◽  
South Wales ◽  
Wide Range ◽  
Thermal Relations

A field study of the thermal relationships of the small agamid lizard A. fordi has been carried out in two areas of mallee in central western New South Wales, where this lizard occurs only in close association with the grass Triodia scariosa. The body temperatures characteristic of various phases in this lizard's die1 cycle have been determined. The behavioural techniques employed to regulate temperature are described; they are similar to those used by a wide range of diurnal heliothermic lizards in other regions. The total effect of these thermoregulatory responses is to maintain an internal thermal environ- ment approaching homoiothermy while the lizard is active. For A. fordi the eccritic body temperature determined from animals in the field is 36.9+-0.16C. Lowering of activity thermal levels occurs in winter, and can be induced at any time by even mild starvation.

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