Structural Damage Warning Criterion For Double Wall-Eared Gallery Impacted By Falling Stone Based On Acceleration Signal

With the rapid development of high-speed railway in west China,Propotion of tunnels in the line is gradually increasing.To reduce the dangerous falling rocks’ influence on railway operation safety,entrance of tunnels are needed to be lengthen by vaulted gallerys or by hangar tunnels.Hence the occurrence time and energy of falling stone impaction are random and difficult to predict,solid gallery structures are still at the risk of being smashed by high-energy falling stones.In order to avoid the sudden danger of racing line being stucked by lacking of konwledeg about the site situation,or to avoid the unnecessary costs by blindly breaking railway traffic,gallerys at the risk of falling stone disaster require an accurate real-time structure damage monitoring system.There is still no such a monitoring system for gallerys already be used in the Chinese railway network,and the same is ture for researches about this monitoring system in China.To compensate for the lack of research in this area,this paper is written in co-ordination with the research of “railway tunnel gallery rockfall damage monitoring theory and application method based on acceleration signal” by the author under tutor’s guidance.Method of Abaqus Explicit finite element analysis was used to analyze damage condition of gallery models with buffer layer thickness of 1m,2m and 3m separately after the impact of falling stone with different level of sizes and initial velocities.Average damage factor of arc part C35 concrete component units are used as a quantitative index for comparedthe structure damage,Quantitative relation curves are fitted between this index and the kinetic energy of rockfall.According to the crack propagation of the tensile damage nephogram,the structural damage condition of all conditions is defined as 4 damage levels with the settlement of vault as the ruler.The relation table between damage and rockfall condition is plotted.Taking the nodes corresponding to the model as the monitoring point,the acceleration time curve of the monitoring node was taken as the monitoring signal,and the acceleration signal energy at the first second of impact was calculated as the signal interpretation index.The relation table between the signal distribution feature of the longitudinal and transversal monitoring points and the damage grade of the structureis plotted,which is regarded as the qualitative judgment standard of structural damage.Quantity relation curves between the representative signal energy value and kinetic energy of the stone was fitted,so the quantitative relationship between the representative signal energy value and the damage degree of quantitative indicators can be obtained indirectly as an accurate judgment after the qualitative damage classification.This research has important theoretical significance of the monitoring and early warning system of gallery rockfall impact study with independent intellectual property rights and the future development of the structure of open tunnel rock fall proof design.