Papers by Author: Wang Ping

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Authors: Hao Xu, Wang Ping, Jing Mang Xu
Abstract: The finite element method was used to analyze the deformation and stress of track in different length and height of gaps under the train load. In order to study the influence of gap between the slab and emulsified cement asphalt mortar of china railway track system II slab track on the subgrade, a model of CRTS II slab track was established on the base of elastic foundation beam theory and finite element software ANSYS. The results show that gap between slab and CA mortar has significance effect on the stress and deformation of track structure. The deformation of rail and slab, the longitudinal stress of slab were increase with the increase of gap length, but has less effect on lateral stress of slab. When the length of gap exceed to 1.95m, the deformation and stress have the tendency of increase sharply, the length of gap between slab and CA mortar should not exceed 1.95m. The gap between slab and CA mortar has effect on the durability and lifetime of ballastless track, so the gap should be maintenance timely.
Authors: Rong Chen, Wang Ping
Abstract: Based on principle of vehicle-track-bridge dynamic interaction, a dynamic simulation model of a high-speed electric multiple units (EMUs) passing over turnout on bridge was established. The calculation focused on 200km/h No.12 improved ballasted turnout (60kg/m rail) being laid on 3×32.0m simply supported beam, it analyze dynamic characteristics of a freight train with 25t axle load passing at speed of 120km/h and those of CRH1 EMUs passing at speed of 200km/h. Results show that: when the freight train passes the turnout through the main line, the vertical stiffness of the simply supported beams is not sufficient due to the relatively high speed and large axle load; when the EMUs passes the turnout on bridge, the dynamic deflection change rates of girders at the switch and frog are great and the turnout is not appropriately set on the bridge, so the frog crosses over the beam gap, which results in the increasing of track irregularity and finally causes derailment coefficient of vehicle to overrun to reduce the running safety; when a train passes the turnout zone on bridge, interaction between the vehicle and turnout is significant because of load fluctuation of the wheel caused by inevitable structural irregularity at the switch and nose rail, and this requires strengthening measurement and running within speed limit.
Authors: Rong Chen, Wang Ping, Shun Xi Quan
Abstract: In order to study dynamic behavior of vehicle-turnout-bridge coupling system, a vehicle-turnout-bridge dynamic analysis model is established by employing the dynamic finite element method (FEM). When No.18 crossover turnouts(with a speed of 350km/h) are laid symmetrically on the 6×32m continuous beam, influences of turnout/bridge relative position and wheel/rail contact relation in turnout zone on the system dynamic responses are analyzed. The result shows that: wheel/rail contact of turnout zone (especially the frog) has great effect on dynamic responses of turnout on bridge, thus the nose rail height of frog should be optimized to mitigate the wheel load transition and its longitudinal gradient. In terms of the 32m-span continuous beam, the best relative position is frog part of turnout arranged in the range of 1/8 and 1/4 of span.
Authors: Liu Hao, Wang Ping, Le Yan, Wei Luo, Rong Chen
Abstract: The high pier and large-span bridge is high, soft, and have large contact area with the outside world, under the action of wind load, it will occur large vertical and horizontal displacement .This displacement effect on the track structure and will cause rail additional force, lateral displacement and create initial track irregularities, and then reduce the lateral stability of track structure. In this paper, through the large finite element software, we build pier-beam-track model to simulate and analyse the influence on the track structure under the vertical and horizontal wind load, it reached the following conclusion: horizontal wind load basic does not cause rail additional force, but reduce the rail lateral stability; longitudinal wind load can make rail produce certain vertical additional force, but compared to the telescopic additional force, the force basic can be ignored.
Authors: Rong Chen, Wang Ping, Xian Kui Wei
Abstract: Railway turnout, an integrated mechatronics equipment of track technology, is one of key equipments that control the running speed of high-speed railway. During the conversion of turnout, the friction, inclusion of foreign matter and deficient displacement of conversion caused by its own structural characteristics may lead to severe wheel/rail impact. In order to study the influence of conversion deviation on safety and comfort of a train during passing the turnout, train/turnout dynamic model was applied. Taking No.18 turnout on a Passenger Dedicated Line (PDL) with 350km/h as a case study, when the train passed it, the influences of its deficient displacement and inclusion of foreign matter on the following dynamic responses were studied, i.e. wheel load distribution, wheel flange force, dynamic stress of rail, wheel unloading rate, derailment coefficient, as well as the lateral displacements of switch rail and nose rail, etc. Result shows that: (1) the deficient displacement and the inclusion of foreign matter will severely influence the normal operation of the turnout, so the safety and comfort during the train passing through turnout may be affected; (2) During the conversion of turnout, its deficient displacement should be controlled properly, and the foreign matter should be removed during routine maintenance, moreover, a reliable detection system should be set.
Authors: Rong Chen, Wang Ping, Hao Xu
Abstract: A high degree of integrity is the most remarkable feature that makes double-block ballastless track different from other ballastless track structure. Based on the beam/plate theory on elastic foundation, influences of several structural parameters (such as size of track slab and support layer, support stiffness of the subgrade, etc) on stress of the ballastless track system under the axle load of 300kN were studied in order to obtain further understanding of the mechanic performance of double-block ballastless track under the train load. Results show that: structure of double-layer combined structure should be adopted to decrease the stress of each layer of ballastless track; the width of support layer should be less than 3.6m; because the ratio of track slab stress to support layer stress is larger than the ratio of their strength, the width of track slab in the double-layer separated structure should be 280mm or less.
Authors: Rong Chen, Wang Ping, Zhe Liu
Abstract: CA mortar is a key component of slab track. It is used as the material for leveling damping structure layer between the rigid track slab and concrete trackbed of slab track in high speed rail. In order to determine functions of CA mortar with low elastic modulus (EM), the beam/plate theory on elastic foundation was applied to the calculation of slab track’s stress. Under the bonding or no-bonding condition, the influence of CA mortar’s EM on the warping stress and displacement of track slab were calculated. Stress distribution of CA mortar under the common effects of train load and temperature gradient was explored, and the intensity requirement of CA mortar with different EM was put forward. Calculation results show that longitudinal and lateral bending moments of base plate both increase with the increasing of CA mortar’s EM; when the CA mortar’s EM is in the range of 50~10000MPa, there is gap between track slab and the mortar and the deformation of CA mortar (50mm thick) is not enough to compensate the warpage of the track slab; with the increasing of CA mortar’s EM, the tensile and compressive stresses of CA mortar both increase under the common effects of train load and temperature gradient, thus higher requirements on tensile and compressive strength are demanded when CA with high elastic modulus is used.
Authors: Rong Chen, Wang Ping, Bin Wang
Abstract: Based on turnout/bridge interaction principle and finite element method (FEM), an integrated turnout/beam/pier model of jointless turnout on ballasted track was established to analyze the influences of expansion joint on stress and deformation of the turnout. The results are concluded as follows: whether the rail expansion joint is set in front of or behind the turnout, expansion additional force of stock rail will be reduced greatly at the end of the beam; so do the expansion displacement of switch rail and nose rail, the stress of displacement restrictor and spacer block, rail break gap and the longitudinal force of one rail after the other rail broke. But when the expansion joint is set in front of the turnout, the pier’s longitudinal force of continuous beam bridge and the simply supported beam bridge (within the expansion range of the device) increase greatly. When the device is close to the turnout, longitudinal relative displacement of the stock rail to the girder also increases a lot. By comparison, it is more favorable to set the expansion joint behind the turnout, or to set the device at the both ends of the continuous beam, or to set the device at the ends of continuous beam rather than in the center of the span.
Authors: Rong Chen, Wang Ping, Wei Hua Zhao
Abstract: According to mechanical characteristics of welded turnout on continuous-slab-track and bridge, an integrated turnout/track slab/beam/pier finite element model was established to analyze the interaction between welded turnouts on continuous-slab-track and bridge. The study focused on No.18 turnout (60kg/m rail) with movable frog being laid on a (32+48+32) m continuous beam, expansion additional force and braking additional force of the turnout were calculated when the temperature dropped. The results show that the longitudinal interaction between welded turnouts on continuous-slab-track and bridge is small, which presents a reasonable structure type of welded turnout on bridge; in calculation of the expansion force, when the temperature drops, the shrinkage and creep of the base-slab and longitudinal stiffness reduction caused by the cracking are considered, so the results are more representative than those from the case of rising temperature. Therefore, the case of temperature dropping should be the main concern in design; under the action of the braking force, stress and deformation of each component within this turnout/bridge system are comparatively large.
Authors: Luo Wei, Wang Ping, Yan Le, Liu Hao, Chen Rong
Abstract: Established the Car Line - Bridge coupling dynamic model, then entered the actual parameters of train, track and bridge structural, obtained the dynamic excitation at the rail bridge pier bottom when the train passes. On this basis, established the pier - soil - building coupling dynamic model by combining finite element method and infinite boundary element method, analysed the vibration characteristics of soil and buildings surrounding the elevated rail way, brought an in-depth study to the effects of elevated rail transit train running on the environment. The results show that: 1)The the environmental vibration induced by elevated rail transit is low-frequency vibration, the vertical ground boils down to low-frequency vibration of 10 - 25Hz, the transverse vibration of housing column is fundamental frequency vibration near 10Hz, the vertical floor boils down to low-frequency vibration of 10 - 25Hz. 2) The vertical ground vibration response level decreases with the increase of distance to the rail centerline when the train passes. 3) With the increase of vibration wave propagation distance, components of higher frequency decay more quickly.
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