橡胶颗粒改良流态粉煤灰路基隔振性能研究

Investigation on the vibration isolation performance of flowable fly ash subgrade improved by rubber particles

为解决铁路列车运行引发的路基与地基振害问题,基于阻尼耗能原理设计一种新型橡胶颗粒改良流态粉煤灰(FAR)路基。通过室内配合比试验,制备满足工程路用性能要求的FAR路基材料;采用瞬态激振方法测试FAR路基材料的阻尼比,分析橡胶颗粒掺量对FAR路基材料阻尼特性的影响规律,揭示FAR路基的阻尼耗能机理;采用COMSOL有限元软件建立轨道-路基-地基三维耦合数值模型,对比研究普通路基与橡胶颗粒掺量为5%、10%和15%的FAR路基动应力和振动加速度的传播规律,分析验证FAR路基的隔振性能。研究结果表明:橡胶颗粒的掺入降低了FAR路基材料的强度和干密度,掺量不超过固体混合料质量的15%时,路基基本物理力学性能可满足铁路工程应用要求。橡胶颗粒的黏弹特性使FAR路基内部动应力发生损耗或衰减,路基阻尼比随橡胶颗粒掺量增加而增大,且橡胶颗粒掺量相同时,橡胶颗粒粒径越小FAR路基的阻尼比越大,推荐采用150目橡胶颗粒。相比普通路基,FAR路基基床底层、路基土体和地基土体的动应力均有减小,衰减幅值为10%~30%,可有效避免路基动弹变形、地基振陷等灾害发生;FAR路基振动主频范围内地面振动加速度级减小2~6 dB,最高达到83 dB,验证了新型FAR路基的良好隔振性能。研究结果可为铁路FAR路基的隔振设计与铁路路基的安全运营提供参考。

In order to solve the problem of subgrade and foundation vibration damage induced by railway train operation,a new type of flowable fly ash subgrade improved by the rubber particles(FAR)was designed based on the principle of damping energy dissipation.The FAR subgrade material,satisfying the requirements of the engineering performance,was prepared by laboratory mixture tests.By using the transient vibration excitation method,the damping ratio of the FAR subgrade material was tested,the influence of the rubber particles on the damping characteristics of FAR subgrade material was analyzed,and the damping energy dissipation mechanism of the FAR subgrade was revealed.A 3D coupled numerical model of track-subgrade-foundation was established by COMSOL finite element software.The dynamic stress and vibration acceleration propagation laws of the FAR subgrade when the rubber particle content was 5%,10%and 15%were compared with those of the ordinary subgrade,and the vibration isolation performance of the FAR subgrade was analyzed and verified.The results show that the strength and dry density of the FAR subgrade material are reduced with the addition of the rubber particles,and the basic physical and mechanical properties of the subgrade can satisfy the requirements of railway engineering applications when the rubber particle content does not exceed 15%of the solid mixture mass.The viscoelastic characteristics of the rubber particles can cause the loss or attenuation of the dynamic stress in the FAR subgrade and the subgrade damping ratio increases with the increase of the rubber particles.When the rubber particle content is the same,the smaller the rubber particle size is,the larger the damping ratio of the FAR subgrade would be.On this basis,the mixture with 150 mesh rubber particles was recommended.As compared to the ordinary subgrade,the dynamic stress levels in the subgrade bed bottom layer,subgrade soil,and foundation soil of the FAR subgrade all reduce,and the attenuation amplitude ranges from 10%to 30%,which can effectively avoid reducing the occurrence of the subgrade dynamic deformation,foundation vibration settlement and other problems.In the main frequency range of the FAR subgrade vibration,the ground vibration acceleration level is reduced by 2 to 6 dB in general while it can reach as high as 83 dB,which verifies the good vibration isolation performance of the new FAR subgrade.The research results provide reference for the vibration isolation design and the safe operation of the railway FAR subgrade.