Analysis of the influence of CA mortar layer void on the dynamic performance of high-speed trains

The void of cement asphalt (CA) mortar layer will aggravate the abnormal vibration of high-speed trains at the void position and threaten the running safety. Few studies have been conducted on the effect of mortar layer void on the dynamic performance of slab track on bridges and the damage limits. Aiming at the practical problem of CA mortar layer void in track-bridge systems, a dynamic response calculation program for the train-track-bridge system is prepared based on the train-track-bridge interaction theory. A sample library of high-speed trains running performance indicators considering random initial track irregularity under CA mortar layer void conditions is constructed. The influence of void length on the dynamic performance of high-speed trains under two different CA mortar layer void conditions is investigated by means of sample upper bounds based on probability guarantee rate. The results show that the wheel load reduction rate and vertical acceleration of high-speed trains are more sensitive to changes in void length than the derailment coefficient. The effect of CA mortar layer void on the running performance index of high-speed trains is significantly enhanced after a certain critical void length value, railway maintenance should pay more attention to critical thresholds. The mid-span void and beam-end void length thresholds of CA mortar layer based on the probability guarantee rate decrease significantly with the increase in running speed while utilizing the wheel load reduction rate as the control index. However, the void position has little influence on the void length threshold. The void length threshold results can provide a basis for the CA mortar void limits.