Academic literature on the topic 'Track deformation'
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Journal articles on the topic "Track deformation"
1
Sheng, Xingwang, Weiqi Zheng, Jianxian Wu, and Handong Zhang. "Influence of Local Deformation Mode of Cable-Stayed Bridge on Unballasted Tracks: Experimental Research." Advances in Civil Engineering 2020 (February 18, 2020): 1–10. http://dx.doi.org/10.1155/2020/2316524.
Full textAbstract:
The complex local deformation modes of the cable-stayed bridge influence the deformation characteristics of the unballasted tracks laid on it. In this work, a large-scale segment model of a cable-stayed bridge was fabricated, and the maximum upward bending deformation mode of the cable-stayed bridge was realized by multipoint loading on the segment model to study the deformation behaviors of the unballasted tracks. Experimental results indicated that the nonlinear behaviors of the rubber isolation layers are apparent with the loading increased, and the interlayer behaviors of the unballasted track can be improved by the rubber isolation layer. Besides, the relative tensile deformations at interlayers of the unballasted track are inevitable. It is noted that no void and silt form at interlayers of the unballasted tracks with rubber isolation layers due to the precompressions of the rubber material. However, it is entirely possible to produce some diseases such as voids and silts at interlayers of the unballasted track with the geotextile isolation layers paved on the cable-stayed bridge. Furthermore, it is feasible to use the elastic isolation layer to improve the interlayer deformation characteristics because a particular elastic buffer is provided at interlayers of the unballasted track.
2
Pang, Zhiqiang, Mangmang Gao, Guolong Li, Jingjing Yang, and Fei Yang. "The Wavelength Characteristics of Vertical Deformation and a Train Dynamics Simulation of Long-Span, Cable-Stayed Bridges Under Complex Loads." Applied Sciences 15, no. 1 (2024): 133. https://doi.org/10.3390/app15010133.
Full textAbstract:
Ballastless tracks have a high smoothness, but the corresponding laying requirements are strict. Therefore, the maximum span of cable-stayed bridges that can accommodate ballastless tracks is 392 m. For laying ballastless track structures over larger spans, the deformation characteristics of long-span, cable-stayed bridges under complex loads are incompletely understood, and the interaction between them and long-span track–bridge structures is unclear. The influence of the wavelength of the cosine wave on the track–bridge mapping of different orbital structures was explored. The wavelength characteristics of vertical deformation under complex loads were investigated. The track–bridge integrated model for the cable-stayed bridge was established to analyze the mapping relationship between the rail and the bridge and the wavelength characteristics of deformation. Based on the mapping relationships and the wavelength characteristics of deformation, the train–track–bridge dynamics simulation model was simplified. The results show that, when the minimum wavelength of bridge deformation surpassed 6 m, 10 m, and 16 m, the rail deformation in the ballasted track, the longitudinal-connected track, and the unit slab-type ballastless track accurately mirrored the deformation of the bridge. For the span of bridges ranging from 200 m to 600 m, the wavelength of vertical deformation ranged from 21 to 1270 m under complex loads. During local loads, the vertical deformation below the 200 m wavelength constituted a significant proportion near the pie. Considering the influence of the deformation on the train vibration response, the train–bridge dynamic coupling model can be employed to treat the track structure as a load to reduce the complexity of the model and enhance the calculation efficiency.
3
Li, Guolong, Mangmang Gao, Fei Yang, Zilong Wei, and Jingjing Yang. "Study on the threshold for superposed deformation of simply supported bridge creep and track slab upwarp in high-speed railway." Advances in Mechanical Engineering 14, no. 12 (2022): 168781322211439. http://dx.doi.org/10.1177/16878132221143913.
Full textAbstract:
Based on long-term inspection data about track geometric irregularity of 32 m-span simply supported girder bridge in China Railway High-Speed for nearly 10 years, it is found that there is continuous periodic track longitudinal level (TLL) with different wavelengths, thereinto, simply supported girder bridges creep and ballastless track slab upwarp are the primary reasons. Moreover, there are two types of variation trends for bridge creep of 32 m simply-supported bridges with ballastless track, that is, stable type and increasing type, and the maximum [Formula: see text] (the peak-to-peak value of track longitudinal level) is 7.1 mm for track longitudinal level caused by bridge creep, and the maximum [Formula: see text] caused by upwarp deformation of ballastless track slab is 3.2 mm. Hence, this paper investigated the effects on running performance and structure service performance of random track irregularity and additional track irregularity caused by bridge creep, track slab upwarp deformation or superposition of both, a three-dimensional finite element model of vehicle-track-bridge for dynamic simulation calculation was established, the threshold values for bridge creep and track slab deformation under 350 km/h were proposed based on running performance and structure service performance. Finally, research results show that bridge creep influences on the ride comfort significantly, but running safety barely. Due to the short wavelength of TLL, the track slab upwarp deformation affects both the ride comfort and running safety heavily. The car bodies are more sensitive to bridge creep and produce mainly low-frequency vibration, but the rate of wheel load reduction is more sensitive to the track deformation and shows the high-frequency vibration. For 32 m simply supported bridges without track slab deformation, the [Formula: see text] caused by bridge creep should be limited to 7 mm, and 9 mm in difficult situations. When the [Formula: see text] caused by bridge creep is small (less than 5 mm), the [Formula: see text] caused by track slab upwarp deformation must be less than 4 mm. When both deformations exist simultaneously, the [Formula: see text] caused by superposition deformations of both should not exceed 10 mm, with track slab upwarp deformation not exceeding 4 mm. In the presence of both structural deficiencies, it is suggested that the track slab deformation must be eliminated when it is difficult to eliminate the bridge creep.
4
Chen, Zhaowei. "Evaluation of longitudinal connected track under combined action of running train and long-term bridge deformation." Journal of Vibration and Control 26, no. 7-8 (2019): 599–609. http://dx.doi.org/10.1177/1077546319889855.
Full textAbstract:
With long-term operation of high-speed railways, bridge deformation is hard to avoid, which directly affects the mechanical property of longitudinal connected track. To ensure the structural stability of longitudinal connected track and operation safety of train, this work proposes a work to evaluate longitudinal connected track under combined action of running train and long-term bridge deformation. First, the methodology of evaluating longitudinal connected track subject to train load and long-term bridge deformation has been proposed, in which an accurate train–track–bridge dynamic model and the method to determine long-term bridge deformation are settled. Then, the long-term bridge deformations caused by concrete creep, shrinkage, temperature, and pier settlement are investigated. On this basis, the evaluation of longitudinal connected track subject to long-term bridge deformation and running train is conducted, and the safety value of pier settlement for Chinese high-speed railways with longitudinal connected track is suggested. Results show that the long-term bridge deformations are even larger than the amplitude of random rail irregularity. With smaller settlement, influences of creep, shrinkage, and temperature play the leading role in affecting the mechanical behavior of longitudinal connected track, while influence of pier settlement occupies the dominant position with larger settlement. It is suggested that the pier settlement for Chinese high-speed railways with longitudinal connected track should be less than 7.7 mm to ensure structural stability of track and operation safety of train.
5
Yuldashev, Akmal Temirovich. "WHEEL TRACK DEFORMATIONS IN ASPHALT CONCRETE PAVEMENTS." Educational Research in Universal Sciences 1, no. 7 (2023): 173–76. https://doi.org/10.5281/zenodo.7508420.
Full textAbstract:
The article describes the reasons for the appearance of wheelbase deformations that occur on roadways with asphalt concrete pavement, their types and methods of their elimination, which are theoretically hit and analyzedasphalt concrete pavement, roadbase, operation, loads, deformation, wheel track deformations.
6
Sysyn, Mykola, Ulf Gerber, Vitalii Kovalchuk, and Olga Nabochenko. "The complex phenomenological model for prediction of inhomogeneous deformations of railway ballast layer after tamping works." Archives of Transport 47, no. 3 (2018): 91–107. http://dx.doi.org/10.5604/01.3001.0012.6512.
Full textAbstract:
The given article considers the method of calculating the track geometry deformation with respect to uneven accumulation of residual deformations along the track. The technique proposes two significant changes in existing approaches to calculating the efficiency of the ballast layer. The transition from the approach of allowable stresses design in the ballast layer to the deformative approach of accumulations of track geometry deformations allows us to draw conclusions regarding the intervals of track tamping and the duration of ballast layer life cycle. The transition from the determinative to probabilistic approaches makes it possible to draw conclusions not only from the average unevenness, but also with regard to all possible facts of unevenness. The method is based on the mechanism of sudden and gradual deformations occurrence, which depends on a number of key factors: dynamic stresses on the ballast, non-uniformity of track elasticity, performance of current maintenance work. Based on the experimental studies results, the dependencies of sudden deformations and the intensity of gradual deformations on the level of stress on the ballast layer were established. The experimental results of the influence of the sub-ballast base elasticity on the intensity of accumulation of residual deformations are shown. On the basis of the developed method, the prediction of track geometry deterioration for a given structure of the track, the rolling stock and the permissible level of geometric deviations for track maintenance is presented.
7
Li, Zai-Wei, Xiao-Zhou Liu, and Yue-Lei He. "Identification of Temperature-Induced Deformation for HSR Slab Track Using Track Geometry Measurement Data." Sensors 19, no. 24 (2019): 5446. http://dx.doi.org/10.3390/s19245446.
Full textAbstract:
Slab track is widely used in many newly built high-speed rail (HSR) lines as it offers many advantages over ballasted tracks. However, in actual operation, slab tracks are subjected to operational and environmental factors, and structural damages are frequently reported. One of the most critical problems is temperature-induced slab-warping deformation (SWD) which can jeopardize the safety of train operation. This paper proposes an automatic slab deformation detection method in light of the track geometry measurement data, which are collected by high-speed track geometry car (HSTGC). The characteristic of track vertical irregularity is first analyzed in both time and frequency domain, and the feature of slab-warping phenomenon is observed. To quantify the severity of SWD, a slab-warping index (SWI) is established based on warping-sensitive feature extraction using discrete wavelet transform (DWT). The performance of the proposed algorithm is verified against visual inspection recorded on four sections of China HSR line, which are constructed with the China Railway Track System II (CRTSII) slab track. The results show that among the 24,806 slabs being assessed, over 94% of the slabs with warping deformation can be successfully identified by the proposed detection method. This study is expected to provide guidance for efficiently detecting and locating slab track defects, taking advantage of the massive track inspection data.
8
Mishra, Debakanta, Huseyin Boler, Erol Tutumluer, Wenting Hou, and James P. Hyslip. "Deformation and Dynamic Load Amplification Trends at Railroad Bridge Approaches." Transportation Research Record: Journal of the Transportation Research Board 2607, no. 1 (2017): 43–53. http://dx.doi.org/10.3141/2607-07.
Full textAbstract:
Railroad track transitions such as bridge approaches may experience differential movements due to variations in track stiffness; impact loads due to train speed and excessive vibration; ballast settlement from fouling, degradation, or both; tie–ballast contact condition and gap; and settlement of fill, subgrade, and foundation layers. A research study completed recently at the University of Illinois focused on identifying the major causes of this differential movement and implementing suitable rehabilitation measures to mitigate recurrent problems with settlement and geometry. Transient and permanent deformation trends were observed in track substructure layers at two instrumented bridge approaches along the Amtrak Northeast Corridor. Multidepth deflectometer systems installed through crossties successfully recorded both permanent (plastic) and transient deformations of individual track substructure layers. Strain gauges mounted on the rail effectively measured vertical wheel loads applied during train passage and monitored the support conditions under the instrumented crossties. Track settlement (or permanent deformation) data revealed that the ballast layer was the primary source of differential movement contributing to recurrent settlement and geometry problems. Transient layer deformations recorded under train passage were higher in the ballast than in any other substructure layer. Transient displacement and wheel load data were consistently higher at near-bridge locations than at open-track locations. Rail-mounted strain gauges indicated that load amplification levels were significantly higher at near-bridge locations than at open-track locations.
9
Peng, Hua, Qingchen Tang, Li Zhu, Zichen Li, Haiyang Li, and Guangming Wang. "Deformation Control of Subway Stations under the Influence of the Construction of Deep and Large Foundation Pits with Composite Support Systems." Applied Sciences 12, no. 6 (2022): 3026. http://dx.doi.org/10.3390/app12063026.
Full textAbstract:
The excavation depth of a deep and large foundation pit of a composite support system is 25.5 m, the minimum clear distance from the main structure of the station is 10.6 m and the closest distance to the entrance and exit structure is only 3.6 m. Relying on this project, numerical simulation, field monitoring and other methods are used to study the deformation law of the self-supporting system, the ground settlement and the subway station under construction. Then, the influence of different support parameters on the deformation of the subway station and track is analyzed, and the internal relationship between the deformation value of the station and track and the support parameters is further discussed. The main work and achievements are as follows: (1) Through field measurement and analysis, the deformation history of the station and track in the excavation is studied. The obtained results show that the interbracing + pile–anchor composite support structure has better control over the deformation of adjacent stations and tracks. Comparing the simulated value of station and track deformation with the measured data, it is concluded that the simulated and measured deformation trends remain consistent, and the maximum deformation value corresponds to the middle position of the foundation pit. This confirms the rationality and reliability of the composite support system model. (2) The analysis of the influence of different support parameters on the maximum deformation value of the subway station and track shows that the deformation of the station and track is less affected by the pile diameter of the retaining pile and the size of the interbracing section. It is greatly affected by the embedding depth of the retaining pile and the number of support channels. It is suggested that the optimal parameters should be a pile diameter of 1.0 m, embedding depth of 8 m, four interbracings and an interbracing section of 1.0 m × 1.0 m.
10
Li, X., L. Yan, and G. Huang. "LAND SUBSIDENCE MONITORING WITH MULTI-TRACK SAR DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (August 21, 2020): 313–18. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2020-313-2020.
Full textAbstract:
Abstract. In this study, we investigated wide-area land subsidence in Hebei Plain using 78 C-band Sentinel-1A SAR images acquired from May 2017 to May 2018 covering two tracks. High-precision time series retrieval was performed by NSBAS technology based on a single track. The offset deformation values of two tracks calculated in this paper were −0.09 mm/year, and the multi-track deformation rate was successfully merged. Using the cross-validation of redundant observations in the multi-track overlap area to evaluate the accuracy, and it was found that 90% pixel difference between the two track overlap areas was within 9 mm. The standard deviation was 5.38 mm, and the subsidence trend of the overlap area was consistent. Twenty-four subsidence bowls were extracted, and the maximum subsidence rate reached −62 mm/year.
Dissertations / Theses on the topic "Track deformation"
1
Blanco, Blas. "Railway track dynamic modelling." Licentiate thesis, KTH, Farkost och flyg, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207180.
Full textAbstract:
The railway vehicles are an increasing mean of transportation due to, its reduced impact on environment and high level of comfort provided. These reasons have contributed to settle a positive perception of railway traffic into the European society. In this upward context, the railway industrial sector tackles some important challenges; maintaining low operational costs and controlling the nuisance by-products of trains operation, the most important being railway noise. Track dynamic plays a main role for both issues, since a significant part of the operational costs are associated with the track maintenance tasks and, the noise generated by the track can be dominant in many operational situations. This explains why prediction tools are highly valued by railway companies. The work presented in this licentiate thesis proposes methodologies for accurate and efficient modelling of railway track dynamics. Two core axes have led the development of this task, on one hand, the rail modelling and, on the other hand, the characterisation of the finite length nature of track supports. Firstly, concerning the rail modelling technique, it has evolved under two major premises. On one hand, regarding the frequency domain, it should describe high frequency behaviour of the rail. In order to accomplish with this first premise, a model based on Timoshenko beam theory is used, which can accurately account for the vertical rail behaviour up to 2500 Hz. On the other hand, with respect to the time domain, the response should be smooth and free of discontinuities. This last condition is fulfilled by implementation of the Timoshenko local deformation. Secondly, a model of support that considers its finite length nature is sought. For this purpose, a Timoshenko element over elastic foundation is formulated. Thus, the common model of support, which is based on a concentrated connection, is substituted by a distributed model of support. In this way, several enhancements are achieved; the temporal contact force response is smoothed and a more realistic shape is obtained, the amplitude of the displacement due to the parametric excitation is reduced and the magnitude associated to the ‘pin-pin’ frequency is not overestimated.<br><p>QC 20170522</p>
2
Dareeju, Biyanvilage. "Performance evaluation of unsaturated rail track foundations under cyclic moving wheel load." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/102697/4/Biyanvilage%2520Sampath%2520Sri%2520Sameera_Dareeju_Thesis.pdf.
Full textAbstract:
This thesis developed an alternative laboratory element testing method to evaluate the response of the unsaturated soils of rail track foundations under repeated moving wheel loadings. The novel laboratory testing method is more capable of producing the realistic strength-deformation characteristics of the unsaturated soils with the effects of principal stress axis rotation (PSAR), which can be used to redesign the conservative rail track guidelines.
3
Ghyate, Forsberg Karima, and Rogin Ramak. "Discrete Element Modelling of the Unbound Layer for Slab Tracks on High Embankment." Thesis, KTH, Jord- och bergmekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193139.
Full textAbstract:
According to Swedish guidelines for high speed railways on embankment, the total settlement is limited to 20 mm over a track length of 10 m during the construction service life. The main objective of this thesis was to investigate the deformation in the subgrade (unbound layer) in a slab track, since there are very few studies related to high speed railways on high earth structure, discussing particularly the unbound layer. This thesis examined the unbound layer consisting of granular material by using the discrete element method (DEM) software PFC. There was a focus on the material compaction and deformations due to traffic loading. DEM has the benefit to be able to model deformation with due consideration of processes at microscale level. Two different particle shapes were tested: balls and clumps. The results showed that the settlements were small, possibly associated to the well compacted material and the simplifications in the model, such as the shape of the particles, absence of particle breakage and the applied traffic load. The clump simulations resulted in less settlements and permanent strains compared to the ball simulations. The higher the embankment the more settlements but less strains were produced for all the three simulations. One interesting parameter to study for the balls simulation was the friction between the particles. Increased friction contributed to less settlement. The maximum height of the embankment was limited to around 3,2 m due to time restraints. Simulations for higher embankments are needed to be performed in order to better understand the effect of the embankment height on settlements.
4
Widarda, Dina Rubiana. "Longitudinal forces in continuously welded rails due to nonlinear track-bridge interaction for loading sequences." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1238081328011-05497.
Full textAbstract:
The use of continuously welded rails (CWR) governs the longitudinal stress caused by seasonal temperature changes, bending of supporting structure and braking/accelerating due to passing trains. Those three loads have been regulated in Eurocode1 and accomplished by the national codes like DIN Fb-101 in Germany. An additional loading case identified and treated in this thesis is the load due to a change of the coupling stiffness in longitudinal direction between the track and bridge. This additional load occurs as a consequence of the employment of a nonlinear stiffness law which increases the restoring force by a factor of 3 when the situation of the track changes from ‘unloaded’ to ‘loaded’ due to a passing train. This particular phenomenon has not been mentioned in the codes so far though it is a natural consequence of fundamental conditions in those codes. For CWR the longitudinal coupling between the rail and bridge plays an important role. This coupling interface is created either by a ballast, for a ballasted track, or by a fastening system in the case of slab track. The deformation state of the coupling interface characterizes the behaviour of the system, whether elastic or plastic. Therefore, the nonlinear behaviour is valid for the system. To accommodate the nonlinear nature, a sequential loading analysis is used, taking into account the loading history. As the change situation due to a passing train happens in a short time, the influence of the mass acceleration should be taken into account in the system’s equilibrium. This aspect is investigated by treating the dynamic load as an impulse-like load. However, a realistic load needs some time to affect the whole bridge, thus the continuous change of stiffness is used to simulate the dynamic analysis. There is a lack of information on determining the value of coupling stiffness in longitudinal direction caused by a passing train. Therefore, it is important to evaluate the coupling stiffness from field measurements in order to find reliable values. The implementation of the load onto several typical bridges shows that the change of the coupling stiffness increases the stresses and it should not be neglected. The evaluation of the load due to a change of the coupling stiffness accompanied by bending of the supporting structure gives satisfactory results by using the static analysis only. Thus, a dynamic analysis can be avoided. Multiple cycles of passing trains occurring after seasonal temperature change indicate a significant increase of elastic parts along the track-bridge coupling interface and a decrease in stresses in the rails. Thus the danger of deterioration is reduced significantly<br>Die Verwendung von durchgehend geschweißten Schienen auf Brücken führt zu zusätzlichen Längsspannungen infolge der Lastfälle jahreszeitliche Temperaturänderung, Brückendurchbiegung und Bremsen/Anfahren. Diese drei Lasten sind durch den Eurocode 1 vorgegeben und in die nationale deutsche Norm DIN Fb-101 integriert. In dieser Arbeit wird erstmals ein weiterer Lastfall identifiziert und behandelt, der durch den Wechsel der Koppelsteifigkeit in Längsrichtung zwischen Gleis und Tragwerk bei der Zugüberfahrt begründet wird. Dieser Lastfall wird hier mit „Ruck“ bezeichnet und ist eine zwangsläufige Konsequenz des nichtlinearen Längsverschiebewiderstandes, wie er im EC 1 und im DIN Fb-101 vorgegeben ist. Dennoch wurden die Auswirkungen auf das Systemverhalten bisher nicht untersucht. Bei einem Wechsel vom unbelasteten Gleis zum belasteten Gleis während einer Zugüberfahrt erhöht sich zum Beispiel der Längsverschiebewiderstand für ein Schottergleis um den Faktor 3! Die dadurch bedingte Veränderung des Zusammenwirkens zwischen Gleis und Tragwerk führt zu einer Veränderung des Systemzustandes und damit zu veränderten Schienenspannungen. Für durchgehend geschweißte Schienen spielt die Längskopplung zwischen Schiene und Brücke eine wesentliche Rolle. Beim Schottergleis wird sie dargestellt durch die Einbettung des Gleisrostes im Schotterbett im Zusammenwirken mit der Schienenbefestigung. Bei der festen Fahrbahn durch das Befestigungssystem. Für kleine Deformationen ist die Koppelsteifigkeit proportional zur Relativverschiebung zwischen Gleis und Brücke. Darüberhinaus geht das linear elastische Verhalten in ein quasi plastisches Verhalten mit konstanter Koppelkraft über. Folgerichtig ist die Behandlung einer Lastenfolge nur in inkrementeller Weise unter Einbeziehung der Verformungsgeschichte mechanisch korrekt. Die Lastfälle Bremsen/Anfahren, Brückendurchbiegung und Ruck ereignen sich nur während der Zugüberfahrt; also in relativ kurzer Zeit, dann allerdings mit einem erheblichen Lastgradienten. Somit stellt sich die Frage nach dem Einfluss der Massenbeschleunigungen, die in dieser Arbeit geklärt wird. Die im Fachbericht genanntenWerte für den Längsverschiebewiderstand des belasteten Gleises basieren auf einer relativ geringen Datenmenge. Aus diesem Grund werden die Messdaten einer umfangreichen Feldmessung mit Zugüberfahrten zu Aussagen über den Längsverschiebewiederstand herangezogen und die Problematik derartiger Messungen beleuchtet. Die unterschiedlichen Modellierungen des Lastfalls „Ruck“, einmal rein statisch und zum anderen dynamisch, ergeben übereinstimmende Schienenlängsspannungen für die statische und die kontinuierliche dynamische Variante. Somit kann auf die aufwändige dynamische Analyse verzichtet werden. Mehrere Zyklen von Zugüberfahrten im Anschluss an eine jahreszeitliche Temperaturänderung bewirken einen signifikanten Abbau der Durchrutschbereiche, also eine Erhöhung der elastischen Abschnitte in der Koppelfuge zwischen Bauwerk und Gleis verbunden mit einer Abnahme der Schienendruckspannungen. Somit hilft dieser Effekt dem System, der jahreszeitlichen Temperaturänderung zu widerstehen
5
Widarda, Dina Rubiana. "Longitudinal forces in continuously welded rails due to nonlinear track-bridge interaction for loading sequences." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23616.
Full textAbstract:
The use of continuously welded rails (CWR) governs the longitudinal stress caused by seasonal temperature changes, bending of supporting structure and braking/accelerating due to passing trains. Those three loads have been regulated in Eurocode1 and accomplished by the national codes like DIN Fb-101 in Germany. An additional loading case identified and treated in this thesis is the load due to a change of the coupling stiffness in longitudinal direction between the track and bridge. This additional load occurs as a consequence of the employment of a nonlinear stiffness law which increases the restoring force by a factor of 3 when the situation of the track changes from ‘unloaded’ to ‘loaded’ due to a passing train. This particular phenomenon has not been mentioned in the codes so far though it is a natural consequence of fundamental conditions in those codes. For CWR the longitudinal coupling between the rail and bridge plays an important role. This coupling interface is created either by a ballast, for a ballasted track, or by a fastening system in the case of slab track. The deformation state of the coupling interface characterizes the behaviour of the system, whether elastic or plastic. Therefore, the nonlinear behaviour is valid for the system. To accommodate the nonlinear nature, a sequential loading analysis is used, taking into account the loading history. As the change situation due to a passing train happens in a short time, the influence of the mass acceleration should be taken into account in the system’s equilibrium. This aspect is investigated by treating the dynamic load as an impulse-like load. However, a realistic load needs some time to affect the whole bridge, thus the continuous change of stiffness is used to simulate the dynamic analysis. There is a lack of information on determining the value of coupling stiffness in longitudinal direction caused by a passing train. Therefore, it is important to evaluate the coupling stiffness from field measurements in order to find reliable values. The implementation of the load onto several typical bridges shows that the change of the coupling stiffness increases the stresses and it should not be neglected. The evaluation of the load due to a change of the coupling stiffness accompanied by bending of the supporting structure gives satisfactory results by using the static analysis only. Thus, a dynamic analysis can be avoided. Multiple cycles of passing trains occurring after seasonal temperature change indicate a significant increase of elastic parts along the track-bridge coupling interface and a decrease in stresses in the rails. Thus the danger of deterioration is reduced significantly.<br>Die Verwendung von durchgehend geschweißten Schienen auf Brücken führt zu zusätzlichen Längsspannungen infolge der Lastfälle jahreszeitliche Temperaturänderung, Brückendurchbiegung und Bremsen/Anfahren. Diese drei Lasten sind durch den Eurocode 1 vorgegeben und in die nationale deutsche Norm DIN Fb-101 integriert. In dieser Arbeit wird erstmals ein weiterer Lastfall identifiziert und behandelt, der durch den Wechsel der Koppelsteifigkeit in Längsrichtung zwischen Gleis und Tragwerk bei der Zugüberfahrt begründet wird. Dieser Lastfall wird hier mit „Ruck“ bezeichnet und ist eine zwangsläufige Konsequenz des nichtlinearen Längsverschiebewiderstandes, wie er im EC 1 und im DIN Fb-101 vorgegeben ist. Dennoch wurden die Auswirkungen auf das Systemverhalten bisher nicht untersucht. Bei einem Wechsel vom unbelasteten Gleis zum belasteten Gleis während einer Zugüberfahrt erhöht sich zum Beispiel der Längsverschiebewiderstand für ein Schottergleis um den Faktor 3! Die dadurch bedingte Veränderung des Zusammenwirkens zwischen Gleis und Tragwerk führt zu einer Veränderung des Systemzustandes und damit zu veränderten Schienenspannungen. Für durchgehend geschweißte Schienen spielt die Längskopplung zwischen Schiene und Brücke eine wesentliche Rolle. Beim Schottergleis wird sie dargestellt durch die Einbettung des Gleisrostes im Schotterbett im Zusammenwirken mit der Schienenbefestigung. Bei der festen Fahrbahn durch das Befestigungssystem. Für kleine Deformationen ist die Koppelsteifigkeit proportional zur Relativverschiebung zwischen Gleis und Brücke. Darüberhinaus geht das linear elastische Verhalten in ein quasi plastisches Verhalten mit konstanter Koppelkraft über. Folgerichtig ist die Behandlung einer Lastenfolge nur in inkrementeller Weise unter Einbeziehung der Verformungsgeschichte mechanisch korrekt. Die Lastfälle Bremsen/Anfahren, Brückendurchbiegung und Ruck ereignen sich nur während der Zugüberfahrt; also in relativ kurzer Zeit, dann allerdings mit einem erheblichen Lastgradienten. Somit stellt sich die Frage nach dem Einfluss der Massenbeschleunigungen, die in dieser Arbeit geklärt wird. Die im Fachbericht genanntenWerte für den Längsverschiebewiderstand des belasteten Gleises basieren auf einer relativ geringen Datenmenge. Aus diesem Grund werden die Messdaten einer umfangreichen Feldmessung mit Zugüberfahrten zu Aussagen über den Längsverschiebewiederstand herangezogen und die Problematik derartiger Messungen beleuchtet. Die unterschiedlichen Modellierungen des Lastfalls „Ruck“, einmal rein statisch und zum anderen dynamisch, ergeben übereinstimmende Schienenlängsspannungen für die statische und die kontinuierliche dynamische Variante. Somit kann auf die aufwändige dynamische Analyse verzichtet werden. Mehrere Zyklen von Zugüberfahrten im Anschluss an eine jahreszeitliche Temperaturänderung bewirken einen signifikanten Abbau der Durchrutschbereiche, also eine Erhöhung der elastischen Abschnitte in der Koppelfuge zwischen Bauwerk und Gleis verbunden mit einer Abnahme der Schienendruckspannungen. Somit hilft dieser Effekt dem System, der jahreszeitlichen Temperaturänderung zu widerstehen.
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Anselmsson, Matts Ola. "Inverkan av hjullast och ringtryck på tryck och deformation i jordprofilen, främst i matjorden /." Uppsala : Department of Soil Sciences, Swedish University of Agricultural Sciences, 2003. http://www.mv.slu.se/jb/Publikationer/exjobb/Ex-jobbMattsOla.pdf.
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Battarra, Lorenzo. "Multi-trace deformations in AdS/CFT models of cosmological singularities and condensed matter." Paris 7, 2012. http://www.theses.fr/2012PA077026.
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Grâce à la correspondance AdS/CFT, des phénomènes de gravité quantique peuvent être étudiés en terme de théories des champs non gravitationnelles. Dans un régime différent, AdS/CFT permet une description alternative de certaines théories des champs fortement couplées à travers les propriétés de solutions classiques de supergravité. Dans cette thèse, nous explorons des modèles dans lesquels la correspondance est élargie par l'adoption de déformations multi-trace de la théorie des champs duale. Dans le bulk, ces déformations correspondent à des conditions aux limites non ordinaires pour les champs de supergravité. Dans la première partie de cette thèse, nous étudions une classe de modèles holographiques qui décrivent des singularités gravitationnelles de type "Big Crunch" en termes d'évolution d'une théorie des champs instable. Nous étudions la possibilité, précédemment considérée par d'autres auteurs, de "résoudre" la singularité dans la théorie des champs. Dans la deuxième partie, nous étudions les propriétés thermodynamiques de trous noirs avec champ scalaire dans le cadre de la supergravité N~8 en cinq dimensions. Ces solutions décrivent des états d'équilibre de la théorie des champs dans lesquels, à cause de la présence de la déformation, un opérateur scalaire acquiert une valeur moyenne non nulle. Dans la troisième partie, nous généralisons cette analyse aux trous noirs en quatre dimensions, qui ont récemment été considérés dans les modèles de supraconductivité holographique. Nous calculons le spectre de fréquences quasi-normales scalaires, et proposons une relation entre le mode le moins atténué et les potentiels effectifs construits à partir des données de supergravité<br>The AdS/CFT correspondence provides a framework in which intrinsically quantum gravitational phenomena can be investigated in terms of a non—gravitational field theory. In a different regime, it allows an alternative description of certain strongly coupled field theories via the properties of classical solutions of supergravity. In this thesis, we investigate models in which the correspondence is extended by the use of so-called multi-trace deformations of the dual field theory. In the bulk, these are mapped to non-standard boundary conditions for the supergravity fields. In the first part of the thesis, we study a class of holographic models that describe Big Crunch singularities in the bulk in terms of the evolution in an unstable field theory. We investigate the possibility, previously conjectured by other authors, that the singularity may be resolved on the field theory side. In the second part, we study the thermodynamic properties of hairy black holes in five—dimensional N=8 supergravity. These solutions describe equilibrium states of the dual strongly coupled field theory in which, due to the presence of the multi-trace deformation, a scalar operator acquires a non-vanishing expectation value. In the third part, we generalize this analysis to four dimensional hairy black holes, which have reçently been considered in models of holographic superconductivity. We compute the spectrum of scalar quasi—normal frequencies of these black holes, and propose a relation between the longest lived mode and the properties of effective field theory potentials built from supergravity data
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Mahé, Stéphanie. "Etude de la fracturation et de la déformation d'un massif rocheux aux abords d'une faille d'échelle crustale dans le cadre du tracé du tunnel routier de Saint-Béat." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20254/document.
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Le massif de marbres de Saint-Béat se situe dans la Zone Interne Métamorphique des Pyrénées centrales françaises. Il est formé de sédiments mésozoïques métamorphisés lors de l'événement métamorphique extensif Haute température - Basse pression classiquement décrit dans les Pyrénées. L'objet de cette thèse est de caractériser la déformation ductile et la fracturation qui affectent ce massif, et de déterminer dans quelle mesure les processus responsables de la fracturation peuvent être influencés par l'état de déformation. Les caractéristiques de la déformation des marbres et de ses roches encaissantes seront déterminées essentiellement grâce aux orientations préférentielles des axes de la calcite (marbre) et du quartz (socle paléozoïque), déterminées à l'aide de mesures à l'EBSD. L'observation en lame mince des textures de la calcite permet de quantifier les taux de déformation et d'estimer la température de cette déformation. Combinés aux observations de terrain, ces résultats permettent de proposer un modèle structural retraçant l'évolution du bassin depuis l'extension aptio-albienne jusqu'à son état actuel. La fracturation du massif est ensuite regardée à différentes échelles, depuis la photo aérienne jusqu'à l'affleurement. Quatre zones seront étudiées en détail afin de classifier les fractures par familles de mêmes caractéristiques et de reconstituer localement les paléo-régimes de contraintes. On comparera les tenseurs obtenus avec les régimes tectoniques décrits dans la littérature. Trois faciès légèrement différents de marbre servent de base à une étude visant à discuter de l'état d'anisotropie de la roche. Ainsi, des essais en compression simple, en traction indirecte et des mesures de vitesses acoustiques sont pratiqués sur des carottes orientées réalisées dans ces trois faciès ; leurs résultats donnent accès aux caractéristiques internes de la roche. On comparera et discutera les résultats d'un faciès à l'autre, et au sein du même faciès, d'une orientation à l'autre. Les résultats obtenus sur la fracturation servent de guide à la classification des fractures observées sur les fronts de tirs, lors du creusement du tunnel routier de Saint-Béat, recoupant le massif sur plus d'un kilomètre du Nord au Sud<br>The Saint-Béat massif, composed of different marble facies, is part of the Internal Metamorphic Zone of the French Central Pyrenees. It is formed by Mesozoic sediments metamorphosed by the High Temperature – Low Pressure extensional event, classically described in the Pyrenees. The aim of this work is to characterize the deformation and fractured state of the massif, and to understand how the former can constrain the latter. The ductile deformation state is recorded in calcite grains for Mesozoic rocks, or in quartz grains for Paleozoic rocks. Their preferential lattice orientations have been measured with the EBSD method. Calcite texture observations give indications about deformation rates and temperatures. These results, in addition with field observations, allow us to rebuild the structural evolution of the massif, from the Albian extension. Fracturing along the massif is described at different scales. Four outcrops are selected in order to characterize and to classify fractures, and locally reconstruct the paleo stress tensor. The obtained tensors are presented and compared to those already published. Three slightly different marble facies are used to discuss the degree of anisotropy of the rock. Mechanical experiments such as compression tests, tensile tests and velocity measurements of elastic waves are carried out on oriented cores within these three facies. These results provide internal rock characteristics which are discussed and compared for the three facies, and for different orientations of the cores
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SHIH, CHENG-HUA, and 施承華. "The Research on High-speed Rail Track Deformation Survey." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/2645bj.
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碩士<br>建國科技大學<br>土木與防災研究所<br>107<br>This research is primarily dealing with the influence on the high-speed rails from the increasing service time, artificial activities, and other environmental elements. Also, it will deal with the influence on its running safety and riding comfort from the problems of deterioration and distortion of the rails. All the data obtained in this research came from the collection made by the orbital examination vehicle, and the sections which need adjusting are determined by the High-speed Railroad Company. With the help of the high-precision electronic level and the total station to obtain more precise data, as well as the calculation of track deviation quantity, and the analysis of the data, we can figure out the sections of the track lines which need to be adjusted. The data will then be offered to corresponding department to do the necessary adjustments. After the adjustments, a further surveying will be done to make sure if the rails adjusted meet the required standards. In this study, the data required for orbital adjustment, using the automatic station theodolite and electronic level measurement, can not only meet the requirements of adjusting the accuracy of the track measurement data, but also save manpower requirements and costs, so that the contractor has more construction. The contractor has more space for construction.
Keyword：High Speed Rail, Electronic level, Total station
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CHEN, YI-YU, and 陳逸宇. "The Analysis of Track Deformation of Railway Bridges Under Earthquake." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/17039724249693138348.
Full textBooks on the topic "Track deformation"
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Cardim, Nuno, Denis Pellerin, and Filipa Xavier Valente. Hypertrophic cardiomyopathy. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198726012.003.0042.
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Hypertrophic cardiomyopathy is a common inherited heart disease caused by genetic mutations in cardiac sarcomeric proteins. Although most patients are asymptomatic and many remain undiagnosed, the clinical presentation and natural history include sudden cardiac death, heart failure, and atrial fibrillation. Echocardiography plays an essential role in the diagnosis, serial monitoring, prognostic stratification, and family screening. Advances in Doppler myocardial imaging and deformation analysis have improved preclinical diagnosis as well as the differential diagnosis of left ventricular hypertrophy. Finally, echocardiography is closely involved in patient selection and in intraoperative guidance and monitoring of septal reduction procedures. This chapter describes the pathophysiology, clinical presentation, role of echocardiography, morphological features, differential diagnosis, diagnostic criteria in first-degree relatives, echo guidance for the treatment of symptomatic left ventricular outflow tract obstruction, and follow-up and monitoring of patients with hypertrophic cardiomyopathy.
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Karatasakis, G., and G. D. Athanassopoulos. Cardiomyopathies. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199599639.003.0019.
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Echocardiography is a key diagnostic method in the management of patients with cardiomyopathies.The main echocardiographic findings of hypertrophic cardiomyopathy are asymmetric hypertrophy of the septum, increased echogenicity of the myocardium, systolic anterior motion, turbulent left ventricular (LV) outflow tract blood flow, intracavitary gradient of dynamic nature, mid-systolic closure of the aortic valve and mitral regurgitation. The degree of hypertrophy and the magnitude of the obstruction have prognostic meaning. Echocardiography plays a fundamental role not only in diagnostic process, but also in management of patients, prognostic stratification, and evaluation of therapeutic intervention effects.In idiopathic dilated cardiomyopathy, echocardiography reveals dilation and impaired contraction of the LV or both ventricles. The biplane Simpson’s method incorporates much of the shape of the LV in calculation of volume; currently, three-dimensional echocardiography accurately evaluates LV volumes. Deformation parameters might be used for detection of early ventricular involvement. Stress echocardiography using dobutamine or dipyridamole may contribute to risk stratification, evaluating contractile reserve and left anterior descending flow reserve. LV dyssynchrony assessment is challenging and in patients with biventricular pacing already applied, optimization of atrio-interventricular delays should be done. Specific characteristics of right ventricular dysplasia and isolated LV non-compaction can be recognized, resulting in an increasing frequency of their prevalence. Rare forms of cardiomyopathy related with neuromuscular disorders can be studied at an earlier stage of ventricular involvement.Restrictive and infiltrative cardiomyopathies are characterized by an increase in ventricular stiffness with ensuing diastolic dysfunction and heart failure. A variety of entities may produce this pathological disturbance with amyloidosis being the most prevalent. Storage diseases (Fabry, Gaucher, Hurler) are currently treatable and early detection of ventricular involvement is of paramount importance for successful treatment. Traditional differentiation between constrictive pericarditis (surgically manageable) and the rare cases of restrictive cardiomyopathy should be properly performed.
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Delgado Martín, Jordi, Andrea Muñoz-Ibáñez, and Ismael Himar Falcón-Suárez. 6th International Workshop on Rock Physics: A Coruña, Spain 13 -17 June 2022: Book of Abstracts. 2022nd ed. Servizo de Publicacións da UDC, 2022. http://dx.doi.org/10.17979/spudc.000005.
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[Abstract] The 6th International Workshop on Rock Physics (6IWRP) was held A Coruña, Spain, between 13th and 17th of June, 2022. This meeting follows the track of the five successful encounters held in Golden (USA, 2011), Southampton (UK, 2013), Perth (Australia, 2015), Trondheim (Norway, 2017) and Hong Kong (China, 2019). The aim of the workshop was to bring together experiences allowing to illustrate, discuss and exchange recent advances in the wide realm of rock physics, including theoretical developments, in situ and laboratory scale experiments as well as digital analysis. While rock physics is at the core of the oil & gas industry applications, it is also essential to enable the energy transition challenge (e.g. CO2 and H2 storage, geothermal), ensure a safe and adequate use of natural resources and develop efficient waste management strategies. The topics of 6IWRP covered a broad spectrum of rock physics-related research activities, including: • Experimental rock physics. New techniques, approaches and applications; Characterization of the static and dynamic properties of rocks and fluids; Multiphysics measurements (NMR, electrical resistivity…); Deep/crustal scale rock physics. • Modelling and multiscale applications: from the lab to the field. Numerical analysis and model development; Data science applications; Upscaling; Microseismicity and earthquakes; Subsurface stresses and tectonic deformations. • Coupled phenomena and rock properties: exploring interactions. Anisotropy; Flow and fractures; Temperature effects; Rock-fluid interaction; Fluid and pressure effects on geophysical signatures. • The energy transition challenge. Applications to energy storage (hydrogen storage in porous media), geothermal resources, energy production (gas hydrates), geological utilization and storage of CO2, nuclear waste disposal. • Rock physics templates: advances and applications. Quantitative assessment; Applications to reser voir characterization (role of seismic wave anisotropy and fracture networks). • Advanced rock physics tools. Machine learning; application of imaging (X-ray CT, X-ray μCT, FIB-SEM…) to obtain rock proper ties. This book compiles more than 50 abstracts, summarizing the works presented in the 6IWRP by rock physicists from all over the world, belonging to both academia and industry. This book means an updated overview of the rock physics research worldwide.
Book chapters on the topic "Track deformation"
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Indraratna, Buddhima, Cholachat Rujikiatkamjorn, and Wadud Salim. "Existing track deformation models." In Advanced Rail Geotechnology – Ballasted Track, 2nd ed. CRC Press, 2023. http://dx.doi.org/10.1201/9781003278979-6.
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Hua, Liu, Li Bin, Han Tilei, Fan Xianghui, and Zhang Yongfu. "Influence of ground settlement on stress and deformation of CRTS slab ballastless track." In Frontiers of Civil Engineering and Disaster Prevention and Control Volume 1. CRC Press, 2022. http://dx.doi.org/10.1201/9781003308577-30.
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Shtykov, V. I., and A. B. Ponomarev. "The Influence of Sand Composition on Railway Track Pumping and Deformation in Winter Period." In Lecture Notes in Civil Engineering. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-0454-9_2.
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Yang, Jiannan, David Thompson, and Atul Bhaskar. "Dynamic Models of Railway Track Taking Account of Cross-Section Deformation at High Frequency." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design. Springer Japan, 2012. http://dx.doi.org/10.1007/978-4-431-53927-8_15.
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Denne, Bernhard, Karl-Heinz Lang, and Detlef Löhe. "Experimental Analysis of the Cyclic Deformation and Damage Behavior of Characteristic Wheel and Rail Steels." In System Dynamics and Long-Term Behaviour of Railway Vehicles, Track and Subgrade. Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-45476-2_11.
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Xu, Ning, Fei Zeng, Anbin Wang, Zhiqiang Wang, Jinzhao Wang, and Tong Ren. "Experimental Study on the Transfer Characteristic and Deformation of Three Types of Combine Track System." In Lecture Notes in Civil Engineering. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2349-6_68.
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Seco, A., P. J. González, F. Ramírez, et al. "GPS Monitoring of the Tropical Storm Delta along the Canary Islands Track, November 28–29, 2005." In Deformation and Gravity Change: Indicators of Isostasy, Tectonics, Volcanism, and Climate Change, Vol. II. Birkhäuser Basel, 2009. http://dx.doi.org/10.1007/978-3-0346-0149-8_17.
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Si, Zheng, Yanbing Wu, Bin Duan, Xingwei Hu, Rongping Tang, and Huiyuan Zhang. "Research and treatment measures on track deformation of bridge crane in main powerhouse of LD hydropower station." In Civil Engineering and Urban Research, Volume 2. CRC Press, 2023. http://dx.doi.org/10.1201/9781003372417-42.
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Zhang, Shoulong, and Tatsuya Ishikawa. "Influence of Frost Heave Induced Track Deformation on Ballast Settlement of Culvert Transition Zone in Freezing Period." In Challenges and Innovations in Geomechanics. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-12851-6_45.
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Branson, Thomas P., and Bent Ørsted. "Generalized Gradients and Asymptotics of the Functional Trace." In Deformations of Mathematical Structures. Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2643-1_23.
Full textConference papers on the topic "Track deformation"
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Zhang, Lele, Xinyu Li, Xianglei Li, Wenhui Han, and Pingping Huang. "A New Method for Resolving High-Precision 3-D Deformation from Multi-Track InSAR." In IGARSS 2024 - 2024 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2024. http://dx.doi.org/10.1109/igarss53475.2024.10641458.
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Lankford, James, and Inderjit Chopra. "A Computational and Experimental Study of Flexible Insect-based Flapping Wing Aerodynamics and Structural Deformation." In Vertical Flight Society 72nd Annual Forum & Technology Display. The Vertical Flight Society, 2016. http://dx.doi.org/10.4050/f-0072-2016-11558.
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Combined flowfield and structural deformation experiments, in conjunction with a coupled computational aeroelastic analysis, were performed for well characterized, low-aspect ratio, insect-based flexible flapping wings at micro air vehicle (MAV) scale. Two-component time-resolved particle image velocimetry (PIV) measurements were performed to determine the evolution of the vortical flowfield about the wing. Additionally, a VICON motion capture system was used to track the passive wing deformations throughout the course of a flap cycle. The experimental flowfield and deflection measurements were compared against the results of the coupled computational fluid dynamics - computational structural dynamics (CFD-CSD) model. The CFD analysis was conducted using an unsteady Reynolds-averaged Navier–Stokes (URANS) solver and the CSD analysis consists of a general purpose multibody dynamics solver capable of modeling geometrically nonlinear beam and shell elements. Overall, the CFD-CSD results showed good agreement with the measured experimental flowfield and wing deformation data. Additionally, the coupled CFD-CSD solver was used to determine the effect of varied chordwise flexibility on the aerodynamic forces and flowfield. For the cases analyzed, decreasing chordwise flexibility was seen to significantly increase aerodynamic lift with minimal impact on aerodynamic drag. Aeroelastic tailoring of the wing may be used to improve wing performance and efficiency.
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Zhang, Lele, Wenhui Han, Zhiwei Jiang, and Pingping Huang. "Precision Assessment for Resolving 3-D Mining Deformation Using Error Propagation Model Based on Spaceborne Single- and Multi-Track Insar." In IGARSS 2024 - 2024 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2024. http://dx.doi.org/10.1109/igarss53475.2024.10641497.
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Davis, David D., and Steven M. Chrismer. "Track Differential Settlement Model." In ASME/IEEE 2007 Joint Rail Conference and Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/jrc/ice2007-40072.
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A study of track settlement behavior at critical transitions such as road crossings and bridge approaches has yielded a model to predict the amount of differential track settlement at these transitions caused by ballast and subgrade deformation. This AAR ballast and subgrade deformation model has been developed from field and laboratory test data, and has been validated with field settlement measurements at bridge approaches where the ballast and subgrade properties were well documented. As an analytical tool the model can determine the rate of track differential settlement at transitions with traffic loading and to predict when tamping is required to correct track geometry. Also the model can determine the relative amount of deformation from the individual ballast and subgrade layers. These capabilities provide a means to assess whether the main source of deformation is the subgrade or the ballast and the best means to reduce differential settlement and decrease the frequency of tamping at these track transitions.
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Zhao, Chunfa, Xiaolin Song, and Xiaojia Zhu. "Temperature Deformation Analysis of CRTS II Ballastless Slab Track." In 2013 Joint Rail Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/jrc2013-2524.
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Two finite element models of CRTS II ballastless track superstructure were developed to simulate temperature deformations of the precast concrete track slab. One of the models considered the fully bonding interface between the track slab and the cement asphalt mortar layers, while the other uses cohesive zone elements to simulate possible interfacial separation and slip. Warp deformations of the track slab under various temperature loads were calculated using both models. Numerical results show that the track slab glued fully to the mortar layers can approximately hold regular geometry shape even if it bears extreme temperature gradient loads. Although deteriorated mortar layers could increase significantly temperature deformations of the track slab, warp deformations of the track slab are still quite small and the rail harmonic irregularities due to the temperature deformations are tiny. It can be concluded that temperature deformations of CRTS II track slab have little effect on running safety and ride comfort of high-speed trains.
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Guo, Qi, Emma Alexander, and Todd Zickler. "Focal Track: Depth and Accommodation with Oscillating Lens Deformation." In 2017 IEEE International Conference on Computer Vision (ICCV). IEEE, 2017. http://dx.doi.org/10.1109/iccv.2017.110.
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Plášek, Otto, Petr Frantik, and Nikola Svobodová. "Track bed design and evaluation methods." In 6th International Conference on Road and Rail Infrastructure. University of Zagreb Faculty of Civil Engineering, 2021. http://dx.doi.org/10.5592/co/cetra.2020.1145.
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Track bed consists of structural layers and subsoil, and in the case of the ballasted track, also the structure comprises ballast bed. Together, this structure creates a layered half-space in which the load from the rail supports is distributed. The paper is focused on static analysis of track bed as a layered half-space structure. Currently, the so-called DORNII method, developed in the Soviet Union in the mid-1950s, is still used for the assessment of the track bed structure. The evaluation of this structure is based on the assessment of the deformation resistance. The deformation resistance is assessed through the value of the deformation modulus of the sub-ballast surface and the subsoil surface. The deformation modulus is measured both in the geotechnical survey and in the acceptance process of construction works. When designing the track bed, the deformation modulus is taken into account as an essential material characteristic. Neither the stress values relative to the depth nor deflection is analysed in the currently used methodology. The DORNII method is empirical but allows calculation of vertical stress and deflection. The authors wondered whether this method would not be too inaccurate because of increasing train speed and axle load. Two methods, analytical and finite element, were chosen for comparison. The article describes the specific analysis procedures and compares their results.
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Dimitrijević, Jelena, Marko Milijić, and Dušan Cvetković. "Railway track deformation resulting from a curve near one level crossing." In Proceeding of scientific-expert Conference on Railway Railcon '24. University of Niš - Faculty of Mechanical Engineering, Niš, 2024. http://dx.doi.org/10.5937/railcon24111d.
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Numerous deformations and failures occur to the railway superstructure within a period of its projected life of use. The rails are the most exposed part of the superstructure for wear. In addition to transferring the vertical load from the vehicle to other elements of the superstructure and substructure, the rail, being in direct contact with the wheel of the vehicle, is subject to several other static and dynamic effects during traffic. In the case of a predicted impact, some procedures can be implemented to minimize rail wear and extend their service life. However, unfavorable circumstances arise, quickly reducing the service life of rails and might contribute to more serious accidents. The investigation focuses on the specific phenomenon of rail's head deformation and track lateral movement at the point of the curvature, when the curvature was placed next to one level crossing. A collection of field data has been studied for a variety of curves. The findings of this study revealed assumption that position of the curvatures in respect to the one-level crossing disrupts the geometry of the track, resulting in rail deformation, is not entirely valid.
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Shan, Yao, Shunhua Zhou, Quanmei Gong, Xiaohui Zhang, and Sihui Xu. "Deformation Response of Metro Tunnels to Adjacent Tram Track Construction." In First International Conference on Rail Transportation 2017. American Society of Civil Engineers, 2018. http://dx.doi.org/10.1061/9780784481257.078.
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Recuero, Antonio M., and José L. Escalona. "Modeling Infinitely Long Flexible Railroad Tracks Using Moving Modes and Krylov Subspaces Techniques." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12828.
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This paper presents a method to model the flexibility of railroad tracks for the dynamic analysis of vehicle-track interaction. In addition to being a complex structure, the flexible track is infinitely long and shows small areas of deformation whose position moves with time. Due to these properties, the efficient modeling of the track as a flexible body in a multibody system formalism is a challenging problem. In this work the model is developed using the moving modes method in combination with Krylov subspaces techniques. The moving modes method that was previously presented by the authors defines the deformation modes in a trajectory frame whose position changes with respect to the flexible track. In this paper the moving modes are selected from a detailed finite element model of the track and a model order reduction technique based on Krylov subspaces. These modes of deformation are adequate to be selected as moving modes since they affect a small area of the flexible body and they are obtained by assuming the load distribution that actually takes place during the dynamic interaction. However, the most interesting property of the Krylov subspace modes is that they can be selected such that the frequency response function of the reduced order model matches that of the full model with the desired degree of accuracy. In this paper a multibody formulation of railroad vehicles and flexible tracks based on the trajectory frame is presented and applied to the numerical simulation of a full railroad car on a track with geometric irregularities.
Reports on the topic "Track deformation"
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Al-Qadi, Imad, Hasan Ozer, Aravind Ramakrishnan, and Ashraf Alrajhi. Pavement Distresses Due to Truck Platoons: A Holistic Analysis. Illinois Center for Transportation, 2023. http://dx.doi.org/10.36501/0197-9191/23-015.
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Currently, AASHTOWare PMED does not contain a framework to compute distresses for loading scenarios like truck platoons. Truck platoons reduce fuel consumption and improve safety while increasing pavement damage because of a reduction in wander and rest period. The important parameters of truck platoons are wander, rest period, and penetration level. Unlike wander, the effect of reduced rest period on permanent deformation and platoon penetration level are not well documented. Rest period (i.e., truck spacing) is a critical parameter in platoons that can be controlled to reduce damage or to improve fuel savings. Unlike fatigue cracking, shorter rest periods resulted in lower permanent deformation through conventional repeated load triaxial testing. However, the test does not entail a representative load stress pulse because of moving loads. This study uses modified triaxial testing equipment to simulate different load pulses. Reduced triaxial compression was critical over the conventional load stress pulse. For all representative pulses, the effect of rest period was similar (i.e., increasing rest period increased permanent deformation). The researchers developed a framework to compute pavement distresses as a function of truck platoon parameters. Truck platoons distributed uniformly on sublanes resulted in the lowest damage, even lower than a conventional trucking operation. Truck spacing of 60 ft is optimal in terms of safety, as the difference in distresses were minimal compared to spacing at 18 ft.
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Ramakrishnan, Aravind, Ashraf Alrajhi, Egemen Okte, Hasan Ozer, and Imad Al-Qadi. Truck-Platooning Impacts on Flexible Pavements: Experimental and Mechanistic Approaches. Illinois Center for Transportation, 2021. http://dx.doi.org/10.36501/0197-9191/21-038.
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Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.
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Starke, Edgar A., and Jr. Investigation of the Role of Trace Additions of Precipitation, Deformation and Fracture on Aluminum Alloys. Defense Technical Information Center, 2001. http://dx.doi.org/10.21236/ada389780.
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Ramakrishnan, Aravind, Fangyu Liu, Angeli Jayme, and Imad Al-Qadi. Prediction of Pavement Damage under Truck Platoons Utilizing a Combined Finite Element and Artificial Intelligence Model. Illinois Center for Transportation, 2024. https://doi.org/10.36501/0197-9191/24-030.
Full textAbstract:
For robust pavement design, accurate damage computation is essential, especially for loading scenarios such as truck platoons. Studies have developed a framework to compute pavement distresses as function of lateral position, spacing, and market-penetration level of truck platoons. The established framework uses a robust 3D pavement model, along with the AASHTOWare Mechanistic–Empirical Pavement Design Guidelines (MEPDG) transfer functions to compute pavement distresses. However, transfer functions include high variability and lack physical significance. Therefore, as an improvement to effectively predict permanent deformation, this study utilized a conventional Burger’s model, incorporating a nonlinear power-law dashpot, in lieu of a transfer function. Key components, including stress increments and the Jacobian, were derived for implementation in ABAQUS as a user subroutine. Model parameters were determined through asphalt concrete (AC) flow number and dynamic modulus tests. Using a nonlinear power-law dashpot, the model accurately characterized rutting under varying conditions. The Burger’s model was both verified and validated to check the accuracy of implementation and representative of the actual behavior, respectively. Initially developed in 1D domain, the validated Burger’s model was integrated into the robust 3D finite element (FE) pavement model to predict permanent deformation. A new load-pass approach (LPA) enabled reduction in computational domain and cost, along with implementing transient loads more efficiently. The combined integration of the LPA and the Burger’s model into the pavement model effectively captured the rutting progression per loading cycle. Moreover, a graph neural network (GNN) was established to extend the prediction power of the framework, while strategically limiting the FE numerical matrix. The FE model data was transformed into a graph structure, converting FE model components into corresponding graph nodes and edges. The GNN-based pavement simulator (GPS) was developed to model 3D pavement responses, integrating three key components: encoder, processor, and decoder. The GPS model employed two-layer multilayer perceptrons (MLP) for the encoder and decoder, while utilizing graph network (GN) technology for the processor. Validation occurred through two case studies—OneStep and Rollout—with results compared against FE model data as ground truth. Results demonstrated that the GPS model provides an accurate and computationally efficient alternative to traditional 3D pavement FE simulations.
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LOAD-CARRYING CAPACITY OF DAMAGED STEEL GIRDER. The Hong Kong Institute of Steel Construction, 2022. http://dx.doi.org/10.18057/icass2020.p.227.
Full textAbstract:
A steel girder bridge over a highway was found damaged by a truck running underneath. The collision damage in the girder was mainly the deformation of the lower flange and the bent of the web plate, but the buckling of the transverse stiffener and the separation of the transverse stiffener from the web were also noted. The influence of the damage on the safety of the bridge had to be evaluated, and yet the load-carrying capacity of a girder damaged by collision has not been investigated very much. In the present study, based on the data obtained from this bridge, the load-carrying capacity of the deformed girder is studied. To be specific, the deformation of the main girder due to collision is reproduced by the finite element analysis and the damaged steel girder is loaded to evaluate the loadcarrying capacity. The result indicates that the collision damage of the girder deformation, even if quite large, would not necessarily threaten the safety of the bridge.