Dynamic Response And Limit Analysis Of Buried Gas Pipeline Under Rockfall Impact

China has vast territory,complex geological conditions,wide transmission pipeline,and the characteristics of large diameter and thin wall of long distance buried pipeline,resulting in frequent accidents due to rockfall in mountainous area.The existing researches have little consideration on the rock volume,velocity,shape and impact mode to buried gas pipeline,in order to improve the research,and provide reliable reference data for the safety evaluation of the rockfall disaster area.Based on previous researchs,ABAQUS is used to the research that dynamic response and limit analysis of buried gas pipeline under rockfall impact,considering various rockfall shape and impact mode.First,the appropriate material models and parameters are selected to establish the finite element model that rockfall impacts soil.The accuracy of the model is verified by comparing the simulation values with the similar test data.On this basis,by analyzing related data of slope rockfall,four representative rockfall volume,speed and impact modes are selected to establish the finite element model of rockfall impact on buried gas pipeline.Second,through the simulation,dynamic response process of buried gas pipeline,variation law of maximum equivalent stress with time,change of the location and shape of the plane at the front of pipeline of different rockfall volume,velocity and impact mode is analyzed.Then,according to the previous research about ground load impacts buried pipeline,pipeline wall thickness,buried depth,distance of pipeline and rockfall drop point are selected as the main factors of rockfall impact on buried gas pipeline in the next simulation.based on the simulation results,maximum equivalent stress and maximum deformation rate of pipeline are calculated.Combination with the failure criterion and instability criterion,critical wall thickness,buried depth,distance of pipeline and rockfall drop point and its relevant Kinetic energy of rockfall is found.Three critical curves of the kinetic energy of rockfall and the main factors are drawn,and the corresponding critical functions are fitted.Finally,results of different impact mode,volume and speed rockfalls impact the west to east gas transportation pipeline of Jiujiang GA049 in mountainous area is forecasted using above achievements,and suggestions about increasing buried depth and dangerous rock control are put forward which are coincident with actual situation.The research achievements may provide technical support of risk assessment and site management on buried gas pipeline in rockfall disaster mountainous area.