Effects of earthquake induced sand liquefaction on dynamic response of high-speed railway train-bridge system

Here, to study effects of earthquake induced sand liquefaction on dynamic response of high-speed railway train-bridge system (TBS) , taking a (88 + 168 + 88) m prestressed concrete continuous rigid frame bridge as an example, Winkler foundation beam was used to simulate pile group foundation, pile-soil interaction was considered with " m method" , and the liquefied soil mechanical index reduction coefficient ty was introduced to simulate sand liquefaction. The finite element model of the whole bridge with pile group foundation was established. Then, based on TTBSAS program, effects of liquefaction depth and degree on dynamic response of TBS were systematically studied, and train driving safety on bridge was analyzed. The results showed that bridge lateral displacement can increase significantly with increase in liquefaction depth, while variation law of bridge lateral acceleration is also related to train speed; the driving safety index increases with increase in liquefaction depth, but its increase range is less than that of bridge displacement, and effects of liquefaction depth on train driving safety on bridge can gradually weaken with increase in train speed; effects of liquefaction degree on dynamic response of TBS is basically consistent to those of liquefaction depth; the train driving safety during it passing through bridge can be overestimated if not considering site sand liquefaction; for the derailment coefficient index, safe speed thresholds considering and not considering sand liquefaction are 275 km/h and 300 km/h, respectively, for the lateral horizontal force index of wheel set, they are 200 km/h and 225 km/h, respectively; the study results can provide a reference for driving safety evaluation of high-speed railway bridges in liquefaction site. © 2022 Chinese Vibration Engineering Society. All rights reserved.