| The study of the interaction between drift ice and bridge piers is an important element of infrastructure operation and maintenance safety in alpine regions,and is also a basic research content for national infrastructure construction,offshore oil exploration,national defense and military construction.With the implementation of "One Belt,One Road" and "Sichuan-Tibet Railway" projects,there are more and more water conservancy projects,transportation projects and marine engineering construction.In alpine regions,river ice will not only block the waterway,but also cause damage to bridges and hydraulic buildings during the opening period.Therefore,the study of dynamic ice force of pier structure of cross-river and crossriver bridges and the pier structure of marine platform has gradually become an important subject of structural engineering anti-ice reaction analysis.During the opening period of rivers in alpine regions,due to the strong dynamic ice pressure and impact force of large ice rows on bridge piers,the bridge pier structure is subjected to different degrees of dynamic damage,and causes deflection and vibration between the main beam and the support,and in extreme cases even causes the collapse of the bridge pier and the main beam to fall off,which seriously affects the normal navigation and transportation of the river.Therefore,in this paper,to address the impact damage of drift ice on bridge piers,a railroad bridge over the Yellow River is used as the research object,and the mechanical properties of the damage of bridge piers by ice load are studied by combining theoretical analysis,numerical simulation and specification verification.The relationship and law,and optimize the design of a universal bridge pier anti-impact ice breaking device.The research in this paper is intended to provide scientific basis for bridge engineering design,construction,operation and anti-icing in alpine regions,and to enrich the connotation of basic scientific research on engineering ice mechanics in alpine regions.In-depth research is conducted mainly on the following three aspects:(1)An integrated method of ice-water-bridge specification verification and numerical simulation is constructed: the study uses energy analysis to verify the validity of the finite element model established in this paper,and the calculated results of the flow ice pressure are analyzed against the numerical simulation results,and then the accuracy of the numerical simulation results is verified.(2)Taking a railroad bridge over the Yellow River as an example,the impact of ice-water coupling on the bridge pier is fully considered,and an ice-water-bridge fluid-solid coupling finite element model is established to study the numerical simulation mechanism of impact damage to the bridge pier by flowing ice in the water medium.LS-DYNA software is used to simulate the collision and extrusion process of the bridge pier by flowing ice in water medium,extract the impact force,impact displacement,velocity,lateral acceleration,equivalent effect variation and other related data of the bridge pier and the stress distribution of flowing ice and the bridge pier during the collision,and analyze the hydrodynamic effect of the structure collision process,the form of flowing ice breaking and the structural response law of the bridge pier and the additional mass block on top of the pier.(3)To investigate the ice row characteristics(drift ice velocity,drift ice strength,drift ice thickness),water velocity and the impact force of drift ice on the bridge pier and its influence law under the condition of the bridge pier set up collision avoidance body,and optimize the design of a universal bridge pier collision avoidance ice breaking device.The final results show that: when the flow ice velocity gradually increases,the flow ice velocity and the flow ice impact force peak,the pier top displacement peak show an approximate linear relationship;when the flow ice compression strength gradually increases,the flow ice compression strength and the flow ice impact force peak,the pier top displacement peak show an approximate polynomial relationship;when the flow ice thickness gradually increases,the flow ice thickness and the flow ice impact force peak,the pier top displacement peak show an approximate linear relationship;when the flow ice thickness gradually increases,the flow ice thickness and the flow ice impact force peak,the pier top displacement peak show a When the water flow velocity gradually increases,the water velocity and the peak impact force of drift ice and the peak displacement of the pier top show a linear relationship;in addition,the pier set up collision avoidance body can reduce 49.6% of the impact force of drift ice on the bridge pier and 59.3% of the lateral displacement of the pier top,indicating that the bridge pier set up collision avoidance body can effectively protect the safety of the bridge structure.A comprehensive analysis of the different conditions simulated in this paper shows that the influence of the water medium in the process of interaction between drift ice and bridge piers is significant and cannot be ignored. |
