循环载荷作用下基床力学特性对道床影响的动态模型试验研究

针对既有线提速改造及高速客运专线设计与施工中遇到的轨道与路基参数的合理匹配问题,以室内动载模型试验研究为依托,配制6组不同密实度的土样,对轨道与路基结构进行了动应力、弹性变形、塑性变形、反应模量等项目的测试,并通过不同压实系数下模型试验测试结果的对比分析,得出基床、道床弹塑性变形以及反应模量的变化趋势,探讨了轨道与路基结构地基系数、压实系数及动静刚度等参数之间的发展规律,提出基床对道床影响的临界值,即:基床压实度为0.93时,基床临界动刚度值为75 MPa/m,基床临界动弹性变形为1.5mm,道床的临界动刚度值为110 kN/mm。对基床与道床参数匹配及相互动力作用的规律研究,为既有线提速改造及新线轨道与路基结构参数设计具有重要意义。

Dynamic Model Experimental Study on Effects of Mechanical Properties of Railway Subgrade Beds on Ballast Beds under Cyclic Loading

Aiming at reasonable matching of parameters of the subgrade bed and ballast bed in speeding-up reconstruction of existing railways and design and construction of special high-speed lines for passenger traffic,a number of laboratory dynamic model tests were carried out with six groups of soil samples of varied compactness and the dynamic stresses,elastic deformations,plastic deformations and reaction moduli of the subgrade and track structures were measured.Through comparison among results of model tests under different compacting factors,the developing tendencies of elastic and plastic deformations and reaction moduli were revealed;the developing regularities of the foundation coefficients,compacting factors,and dynamic and static rigidities of the subgrade and track structures were explored.The critical values of the influences of the subgrade bed on the ballast bed were defined.When the compacted thickness of the subgrade bed was 0.93,the critical dynamic rigidity of the subgrade bed was 75 MPa/m,the critical dynamic elasticity deformation of the subgrade bed was 1.5 mm and the critical dynamic rigidity of the ballast bed was 110 kN/mm. The study of the parameter matching and dynamic interaction between the subgrade and ballast beds is significant in guiding engineering practice.