Study On Longitudinal Force Of CWR In Ballastless Track On High Speed Railway Long Span Bridge

The construction scale of high speed railway in China has grown unprecedentedly because of China's constant increasing efforts in high speed railway development since the eleventh five-year plan. By 2020, more than 16,000 kilometers passenger dedicated lines will be constructed in China. Many long span bridges are in high speed railway and adopt ballastless track and trans-section CWR technology. Because bridge span is large and railway structure is complex on CWR in ballastless track on high speed railway long span bridge, longitunal force is larger than common bridge, which lead to stress and deformation complex. Combined with Jing-Hu high speed railway engineering practical, the finite element model of the whole bridge with double bound railways is established, and longitunal force of the CWR in ballastless track on high speed railway and influence factors have been calculated. The main research contents are as follows:1,Based on principle that interaction between beam and rail on high speed railway long span bridge, the finite element model of the whole bridge with double bound railways for Jing-Hu high speed railway is established. According to the domestic and foreign relevant documents, the model parameters and the loading parameters are selected. Rail, beam and bridge abutment in the model are simulated with beam3 element. Fastener longitunal resistance force is simulated with nonlinear spring combin39 element. Fastener vertical mechanical properties and bridge abutment stiffness are simulated with linear spring combin14 element. Thus deflection force can load directly though the rail.2,By use of the finite element model of the whole bridge with double bound railways for Jing-Hu high speed railway, 10 spans-32m concrete girders as an example, additional expansion force, additional deflection force, braking force and rupture force are calculated and analyesed. When the longitunal forces are calculated, separate interaction is only considered and not stacked influence.3,The additional expansion force, additional deflection force, braking force on CWR in ballastless track on high speed railway long span bridge have been calculated, including the bridge spans, fastener resistance force, bridge pier stiffness and beam temperature changing aspects. While break gap is considered, including fastener resistance force, bridge pier stiffness,beam temperature changing,rail temperature changing and break gap position.The main conclusions of this paper are as follows:1,The additional expansion forces on four rails that are the double bound railways of CWR in ballastless track on high speed railway long span bridge, where temperature load is symmetry, are almost the same. The additional expansion force of rail is large on each bridge abutment and small in the mid-span. On the contrary, the expansion displacement of rail is large in the mid-span and small on each bridge abutment.2,When the train operates on double bound railways of the simply supported girder by the single line, the additional deflection forces on four rails are small and there are tiny difference. The additional deflection force of rail is large on bridge abutment and the longitunal displacement of rail is large in the mid-span and small on bridge abutment.3,The braking forces on four rails are extremely different. The braking displacement of rail is large in the mid-span and small on each bridge abutment, and the braking force is large on bridge abutment and almost zero in the mid-span.4,The longitunal displacement of rail increases obviously by longitunal interaction between beam and rail which caused by fracture rail. On rail break gaps, the displacement and longitunal force of rail change abrupt, but the additional longitunal force and displacement of rail are less influence on far away from the break gaps. The temperature force and displacement on four rails are almost superposition on No.0 bridge abutment.5,Max additional expansion force and additional flexural force are increased with bridge spans, but the range is small. The bridge spans have some influence on braking force of rail, and max braking force is increased with bridge spans. When the bridge spans are the same, the max braking force of load side is larger than unload side.6,Fastener resistance force has great influence on max additional expansion force and additional flexural force of rail, which are increased with fastener resistance force value, and the range is large. Fastener resistance force has less influence on max braking force, which is reduced with fastener resistance force increased on load side and increased with fastener resistance force on unload side.7,Max additional expansion force is increased with bridge pier stiffness, but the increment speed is low. Because the bridge abutment stiffness is larger than bridge pier stiffness, bridge pier stiffness has less influence on max additional flexural force, which is controlled by bridge abutment stiffness. The bridge pier longitunal stiffness has great influence on max braking force, which is reduced with bridge pier stiffness increased, and the range is large.8,Max additional expansion force is increased with beam temperature, and the increment trend becomes slowly when reached a certain temperature.9,Break gap is reduced with fastener resistance force and bridge pier stiffness increased, where reduces fast at the beginning and then tends to slow. Break gap is increased with beam temperature reduced, but the range is small. Break gap is increased with rail temperature reduced, but the range is large. When rail fractures on each bridge abutment, break gap is small. When rail fractures in the mid-span, break gap is large.