桥上CRTSⅡ型板式轨道梁端高强度挤塑板的合理弹性模量研究

Research on Reasonable Elastic Modulus of High-strength Extruded Sheet Laid at Bridge Beam end and Used in CRTS-Ⅱ Slab Track on Bridge

依据梁端CRTS域型板式轨道的结构受力特征，采用梁模拟钢轨、轨道板和底座板，线性弹簧模拟扣件与CA砂浆的弹性作用，采用单向受压弹簧模拟滑动层与挤塑板的支撑作用，建立梁端轨道叠合梁计算模型，分析挤塑板弹性模量对无砟轨道承受轮载以及梁端位移时的受力变化规律。分析表明：由于梁端挤塑板弹性模量相对较低，列车通过时容易引起刚度不平顺、增大轨道受力，应适当提高挤塑板弹性模量；而梁端位移作用时，较大的挤塑板弹性模量则会引起较大的附加弯矩。综合考虑两方面作用，在常用32 m梁上，挤塑板弹性模量在10-0 MPa时，轨道受力状态最佳，其他梁型应根据实际梁端位移适当调整挤塑板弹性模量。

In this research, based on structural and mechanical characteristic of CRTS-II slab track at bridge beam end, a beam-track composite model at bridge beam end was established. In this model, the rail, track slab and base plate were assumed to be beam elements; the fastener and CA mortar were assumed to be linear springs so as to simulate their elastic effect;and the sliding layer and the extruded sheet were assumed to be uniaxial compression springs so as to simulate their supporting effect. Then the change rules of the action effects of both the wheel load and bridge beam end displacement were analyzed with the change of the elastic modulus of the extruded sheet. The analysis shows that： because of the lower elastic modulus of the extruded sheet, there will be uneven stiffness and increased rail stress when train passing through, so the elastic modulus of extruded sheet should be increased appropriately;and on the other hand, because of the higher elastic modulus of the extruded sheet, there will be additional bending moment when displacement angle appearing at bridge beam end. Then this research comes to the conclusion：according to a comprehensive consideration on the two action effects of both the train wheel load and bridge beam end displacement, the reasonable elastic modulus of the extruded sheet should be in the range of 10 to 50 MPa, with which there will be a best stress state of the slab track on the widely used 32-m bridge beam; as for other bridge type, the elastic modulus of extruded sheet should appropriately be adjusted according to actual bridge beam end displacement.