Passenger Green Bridge Transition Section Dynamic Characteristics Of The Experimental Study And Numerical Analysis

The line's easement and the passengers' comfortability are the key indicators of controlling the design of the high-speed railway line. If the road bridge's stiffness has big differences and the line's easement is poor, it will decrease the passengers' comfortability, even endanger the safety. Thus the passing road phase is one of the must key technologies. The thesis has studied the aerodynamic response characteristics of the different structures' road bridge passing phases under the train load influence. It has adopted the combination of three methods: numerical modeling, theoretical research, and field test, on the ground of the QingShen passenger line and on the basis of lots of relevant research at home and abroad. The main jobs include:1. Based on the widespread collection of foreign technical data about design, construction, monitoring, maintenance, experimental study and theoretical analysis of Transition Part of road & bridge, the technical mechanism, design method, exploitation conditions, application effect and the existence question of transition part of road & bridge were thoroughly analyzed, the ground improvement measures which suits the Qinghuangdao-Shenyang dedicated passenger line's special details were proposed.2. Based on the geological conditions and the styles of Qinghuangdao-Shenyang dedicated passenger line, the representative test project were choosed, named geogrid transition part on Guanjiazhuang bridge (DK46+765.95-DK46+790.95) and graded broken stone transition part on Hujiatun bridge (DK44+590.31-DK44+640.31).3. The field test schemes that fit to different passing styles were established, including: deciding the test contents, selecting the measuring element and equipments, the assignment of the test ports and the dynamic test schemes.4. In terms of the test results,the dynamic response characteristics of the different structures' transition part of road & bridge under the different speed were analyzed. The relationships of dynamic stress ,dynamic displacement and acceleration ,and decrease rule with the depth of the subgrade bed. The results indicate the vibration acceleration and dynamic stress increase with the increase of the train speed but mainly within the bedding confination.5. The dynamic analyzing models of different transition styles were established on the basis of the commercial software FLAC(Fast Lagrangian Analysis of Continua in 2 Dimensions),which considering the train load characteristics and the structures of transition part.6.Utilizing the dynamic analysis models, the numeral simulation calculation of transition part's dynamic response under different train speed have done. The results show that the peak value of the dynamic press and the acceleration on subgrade bed were increased with the increase of the train speed ; the subgrade bed dynamic stress decrease with the depth of the subgrade bed. The calculated results is in accord with the field test, the accuracy of analyzing model was testified.7.Field test and the finite difference method were performed, the contrastive analysis on distribution trend of dynamic stress and vibration acceleration of graded broken stone transition part and geogrid transition part. The effect of these two kinds of transition parts were compared.8.The settlement distribution of graded broken stone transition part and geogrid transition part were monitored, whose control effects to post-construction settlement were estimated.