| Vertical columns in alpine regions,such as gate piers,bridge piers and marine platforms,are often threatened by the impact of flowing leveling ice during the opening of rivers in spring,and the huge impact of leveling ice can cause local damage to the vertical column structure or even the risk of collapse of the whole structure,posing a serious threat to the overall safe operation of the structure.The analysis of the response of vertical column structures under level ice loading and the study of the interaction between flowing level ice and vertical column structures are of great significance to ensure the safety of structures and people’s lives and properties.This paper divides the leveling ice into flowing ice and ice row according to the size of the plane,selects a gate pier in the cited Tao project as an example,uses the finite element software ANSYS/LS-DYNA,LS-PREPOST and LS-DYNA SOLVER to model,calculate and process the results,explores the collision characteristics by analyzing the maximum equivalent force,maximum displacement,impact force,acceleration and velocity when the leveling ice hits the gate pier,and also studies the leveling ice The effect of three factors on the collision response,namely the velocity and compressive strength of the flat ice and the plane size,during the impact of the flat ice on the gate pier was also investigated.The main research work in the paper is as follows.(1)The basic theory of flat ice impact on vertical column is elucidated,including the theoretical basis of contact type,contact algorithm,explicit time integration principle and ice-water coupling algorithm in the collision process.Adopt different ice load formulas of many countries to calculate the dynamic ice pressure,verify the accuracy and reliability of the finite element model established in this paper,and compare the calculation results with the numerical simulation results for analysis and research,and discuss the advantages and disadvantages of each formula.(2)Take a gate pier in the cited Tao project as a typical vertical column project example,fully consider the influence of water medium for leveling ice that is ice-water coupling effect,the leveling ice according to the size of the size into flow ice,ice row,establish the gate pier and leveling ice collision numerical simulation model,in the gate pier ice surface is flat,semi-circular,triangle,set the speed,compressive strength,plane size three kinds of working conditions,investigate the leveling ice speed,compressive strength,plane size.To investigate the influence of velocity,compressive strength and plane size of flat ice on the maximum equivalent force and maximum displacement of the impact area of gate pier with different ice surface.(3)For the collision study of drift ice,ice row and gate pier,the final results show that:when the velocity of drift ice gradually increases,the maximum equivalent force and maximum displacement of gate pier impact area and its velocity show a peak curve relationship;when the velocity of ice row gradually increases,the maximum equivalent force and maximum displacement of gate pier impact area and its velocity show a logarithmic function relationship;when the compressive strength of drift ice and ice row gradually increases,the maximum equivalent force and displacement of gate pier impact area show a logarithmic function relationship.When the compressive strength of flow ice and ice row gradually increases,the maximum equivalent force and displacement of the gate pier impacting area and its compressive strength show an approximate polynomial relationship;when the plane size of flow ice and ice row gradually increases,the maximum equivalent force and displacement of the gate pier impacting area show an approximate linear relationship,and according to the maximum equivalent force and displacement of the gate pier impacting area on different ice faces,we can get that the ice breaking ability of different ice faces is: triangle>semi-circle>flat.(4)For the effect of the three working conditions of flat ice flow speed,compressive strength and plane size on the maximum equivalent force in the impact area of the gate pier,sensitivity analysis is carried out to obtain the most sensitive factors of the gate pier with three different ice faces under different working conditions of flow ice and ice row,and response measures are set up for the sensitive factors to control the maximum equivalent force.The final results show that: the sensitivity of uncertain factors from high to low: plane size>flow velocity>compressive strength,in order to improve the safety of long-distance water transmission project in the area prone to the occurrence of Ling disaster,corresponding measures can be taken:(1)measures to reduce the plane size of flat ice;(2)measures to reduce the flow velocity of flat ice;(3)compressive strength for the impact area of the gate pier maximum equivalent force,the impact of displacement is not significant,can be ignored. |
