Dynamic responses of a beam to moving loads on an elastic foundation overlying voids

ZHANG Bingqiang; LI Jiayao; PAN Qinfeng; HUANG Zhibin

doi:10.16186/j.cnki.1673-9787.2023040061

Abstract：Objectives To explore the influence of local voids due to plastic deformation or rainwater erosion on the pavement dynamic responses to moving load,Methods a concrete pavement with local voids was sim-plified as an elastic beam spanning a void,and the equation for the dynamic responses of the elastic beams on the Kelvin foundation with local voids under moving loads was established.The modal superposition method was used to solve the dynamic responses of a beam overlying voids under moving loads.Compared with the calculation results from the existing theoretical methods,the proposed analytical solutions for the dynamic response of foundation beams were verified.The influences of the parameters on the dynamic re-sponse of the beam were studied,including the moving speed of the load,the width of local voids underly-ing the beam,the elastic coefficient of the foundation,and the bending stiffness of the beam.Results Ne-glecting the influence of local voids underneath the beam caused the theoretical results to be less than the true data.The local voids underneath the beam had a significant influence on the dynamic responses of the beam directly above the void,while the influence on the beam outside the void was minor.As the bending stiffness of the foundation beam decreases,the influence of the void width on the maximum displacement of vibration of the foundation beam at the midpoint became significant.When the void width was 2/9 of the length of the beam,the maximum vibrating displacement at the midpoint of the beam was about 5 times of that without considering the void underlying the beam.Increasing the bending stiffness of the beam and the elastic coefficient of the foundation could reduce the vibrating displacement at the midpoint of the beam.However,the effect of improving the foundation elastic coefficient was minor when the void width underly-ing the beam was 1/3 of the length of the beam.Conclusions The local voids underneath the concrete pave-ment exacerbate the vibration of the pavement under vehicle load.