Material Property Test And Vibration Reduction Performance Prediction Of Rubberized Concrete Roadbed

The urban rail transit brings convenience for people,but at the same time,it causes some environmental problems such as vibration and noise,which seriously affects the work and daily life of residents along the line,the safety of surrounding building and the precision of precision instruments and equipment.In order to reduce the impact of the vibration induced by rail transit on the environment,a variety of vibration mitigation measures have been used.But most of these measures simply ruduce the stiffness of the rail system.It increases the investment of rail and worsens the interaction of wheel and rail,which causes abnormal rail corrugation.The abnormal rail corrugation increases the vibration and noise,and it is harmful to the safety operation of rail transit.So some experts suggest that vibration reduction position should be moved down and increasing the quality and damping to reduce the vibration.Rubberized concrete vibration insulating foundation is a new type of vibration mitigation measure.It could absorb the vibration energy because of its material damping characteristics,and its cost is low so it can be used as the base mitigation measure for the whole line to reduce the vibration of the whole line.In vibration sensitive areas,rubberized concrete vibration insulating foundation and other vibration reduction measures could be used at the same time to meet the environmental vibration requirements of the whole line.This dissertation is supported by the projects of National Science Foundation of China named Research on the Vibration Attenuation of Rubberized Concrete Vibration Insulating Foundation(No.51408033).In this dissertation,the rubberized concrete mix proportion applied to rail transit is researched,and the vibration reduction performance of the rubberized concrete monolithic roadbed.Firstly,the mechanical properties and dynamic performance of different mix proportion of rubberized concrete is researched by laboratory test.Rubberized concrete can meet the requirements of rail transit design specifications and has good dynamic performance when the rubber content is not higher than 23%,and it can be used for rail transit vibration reduction.Secondly,3 kinds of mix proportion of rubberized concrete which can meet the requirements of rail transit design specifications and have good dynamic performance are selected,and then the vibration reduction performance of the rubberized concrete roadbed is predicted through the numerical simulation method.Finaly,the selection analysis of rubberized concrete roadbed is done.The main contents and conclusions of this dissertation are as follows:1.The mechanical properties test of rubberized concreteIn this test,the control concrete is C40 concrete.First,15 kinds of mix proportion of rubberized concrete are designed according to different contents of rubber particles,and the compressive strength of rubberized concrete is researched.Then,7 kinds of mix proportion of rubberized concrete is chosed according to the test result,and then the axial compressive strength,static compression modulus,splitting tensile strength and flexural strength of rubberized concrete are researched.The results show that the incorporation of rubber particles can significantly reduce the mechanical properties of concrete,and the greater the rubber content,the more the static performance of concrete decreases.The incorporation of rubber particles can improve the toughness of concrete and reduce the development of cracks in the process of failure.The destruction of rubber concrete is ductile damage.2.The dynamic performance test of rubberized concreteAccording to the results of mechanical properties test,7 kinds of mix proportion of rubberized concrete are chosed.The dynamic performance including dynamic elastic modulus and damping ratio of rubberized concrete is researched.The results show that the incorporation of rubber particles can significantly reduce the dynamic elastic modulus of concrete.The greater the rubber content,the more the dynamic elastic modulus of concrete decreases.The incorporation of rubber particles can significantly increase the damping ratio of concrete.The damping ratio of rubber concrete increases linearly with the increase of rubber content,and rubber content increased by 1%,the damping ratio increased by about 0.023%.Rubberized concrete can meet the requirements of rail transit design specifications and has good dynamic performance when the rubber content is not higher than 23%,and it can be used for rail transit vibration reduction.3.Predictive analysis of the vibration reduction performance of the rubberized concrete monolithic roadbedAccording to the results of mechanical properties and dynamic performance test,3 kinds of mix proportion of rubberized concrete are chosed.The three-dimensional dynamic finite element model of the the rubberized concrete(RC-10,RC-15,RC-23)roadbed and ordinary concrete(SC)monolithic roadbed are set up,and the vibration reduction performance of the rubberized concrete roadbed.The results show that rubberized concrete roadbed has a good vibration reduction performance.The greater the rubber content,the better the vibration reduction performance.The Z-level insertion loss of rubberized concrete roadbed is between 0.34-4.38dB on the surface of 0?30m.4.The selection analysis of rubberized concrete monolithic roadbedUnder conditions of safety,durability and economy,the rubberized concrete roadbed with higher rubber content is more beneficial to a good vibration reduction performance.According to the research results,the rubberized concrete roadbed with 23%rubber content is recommended,and its control concrete is C40 concrete.The single-line cost of rubberized concrete roadbed is about 3.77 million per kilometer,which is basically equal to the cost of general concrete monolithic roadbed track structure.