Abstract The monolithic track bed structure of subway tunnels generally suffers from the separation defect, threat? ing the safe running of the train. In order to analyze the influence of different degrees of separation defects on the dynamic characteristics of the track structure, a finite element simulation model of rail-track bed-tunnel is established in this paper. Based on the investigation results of the separation defects of the monolithic track bed in a subway, the track bed structure with different degrees of separation defects is set up, and the dynamic responses of the rail and track bed under different working conditions are calculated. The conclusions are as follows: 1) Track bed separation defects have occurred in the early stage of subway operation. The separation defects mainly distribute near the expansion joints, and on both ends of the track bed; 2) When the degree of separation is small, the width of the separation is far greater than the displacement amplitude of the track bed, and so the dynamic response of the track structure is hardly affected by changes of the separation width; 3) When the bottom surface of the track bed is not penetrated through by the separation, the vertical displacement increment of the rail and the track bed is limited.However the load-bearing capacity of the track bed will be significantly reduced when the separation is completely through the track bed. The vertical displacements of the rail and track bed have a positive correlation with the length of separation; 4) The track structure vibration will be intensified in varying degrees due to separation of the track bed, and the structural vibration is more sensitive to the change of separation depth.
Abstract：
The monolithic track bed structure of subway tunnels generally suffers from the separation defect, threat? ing the safe running of the train. In order to analyze the influence of different degrees of separation defects on the dynamic characteristics of the track structure, a finite element simulation model of rail-track bed-tunnel is established in this paper. Based on the investigation results of the separation defects of the monolithic track bed in a subway, the track bed structure with different degrees of separation defects is set up, and the dynamic responses of the rail and track bed under different working conditions are calculated. The conclusions are as follows: 1) Track bed separation defects have occurred in the early stage of subway operation. The separation defects mainly distribute near the expansion joints, and on both ends of the track bed; 2) When the degree of separation is small, the width of the separation is far greater than the displacement amplitude of the track bed, and so the dynamic response of the track structure is hardly affected by changes of the separation width; 3) When the bottom surface of the track bed is not penetrated through by the separation, the vertical displacement increment of the rail and the track bed is limited.However the load-bearing capacity of the track bed will be significantly reduced when the separation is completely through the track bed. The vertical displacements of the rail and track bed have a positive correlation with the length of separation; 4) The track structure vibration will be intensified in varying degrees due to separation of the track bed, and the structural vibration is more sensitive to the change of separation depth.
ZHU Lei1 YANG Yan2 RAO Hui1 NIU Pengbo2
.Analysis of Dynamic Response of Track Structure Affected by Different Degrees of Separation of the Monolithic Track Bed in Subway Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2020,V57(6): 107-114
2020, Vol. 57 