Research On Dynamic Characteristics Of Large-scale Aqueduct And Joints Based On Fluid-solid Coupling Method

The South-to-North Water Diversion Project is a large-scale and important national project,and it is also a large-scale project that benefits the country and the people,and is related to the vital interests of hundreds of millions of people.There are 21 aqueducts in the middle route of the South-to-North Water Transfer Project,accounting for 50% of the total aqueducts in the east,middle and west routes.As an important water conveyance structure,the aqueduct’s safety is self-evident to the project.Large-scale aqueducts are affected by natural geological conditions,engineering construction quality,and long-term erosion of water bodies during the operation of the project,and there may be certain hidden safety hazards.Based on this,this paper adopts the research method of combining fluid-structure coupling(CFD/CSD)with ground motion based on the interface data exchange method,and uses the "foundationfoundation-aqueduct structure" as a whole to carry out numerical simulation analysis on the aqueduct structure,and explore the structure Performance evolution law and damage mechanism,and provide corresponding treatment measures and suggestions.By studying the uneven settlement of the transition section structure,analyzing the settlement laws of different parts,and finding the most sensitive position for settlement;by studying the structure performance of the transition section structure under the action of different void volumes and different flow rates after the backfill of the eight-shaped wing wall Damage distribution,explore the hazards of initial defects to the project,so as to better provide theoretical support for the safe and stable operation of the aqueduct.This thesis takes the large-scale aqueducts and joints of the middle route of the South-toNorth Water Transfer Project as the research object,and studies the structural performance evolution law and damage mechanism of the aqueduct structure under various working conditions such as static and dynamic.The main research contents are as follows:(1)By establishing a refined numerical simulation model of the aqueduct for the Southto-North Water Transfer,calculate the natural frequency of the aqueduct structure under the conditions of empty tank,design water level and increased water level,and compare the natural frequency of dry and wet modal structures,and analyze the tank body.The vibration mode of is mainly horizontal and vertical,and the structure is less rigid under the horizontal and vertical conditions.(2)Establish a numerical simulation model for the junction of the channel and aqueduct,and study the uneven settlement between the channel and the transition section structure,the transition section and the lock chamber structure by applying ground stress and water level pressure at different heights,and find that the channel and the transition section are connected The settlement value between these areas is relatively large,and the maximum value appears on the center line of the bottom plate.The settlement observations at and near this place should be strengthened.(3)Establish the infinite element boundary of the large-scale aqueduct,select seismic waves according to site type selection and characteristic period,and process seismic waves,use the additional mass method to complete the ground motion calculation of the additional mass water unit under the design water level,and exchange with interface data Comparing the fluidstructure coupled ground motion calculations of the large-scale aqueduct of the method,the displacement,stress,and damage distributions of the aqueduct structure under the conditions of the additional mass method and the fluid-structure coupling are obtained.The comparison results show that when analyzing the structure’s ground motion response,The simulation calculation using fluid-structure coupling method is closer to real ground motion.(4)In view of the hidden dangers of the project,the middle and upper parts of the middle and upper part of the middle section of the gradation section of the eight-shaped wing wall are set under the design water level to study the structural performance and damage of the eightshaped wing wall at the vacant position under different flow rates.According to the development law,it is found that as the void volume increases,the water flow has a great influence on the structure performance at the void position,and the void is located in the middle section of the transition section.The upper and middle parts of the transition section are completely voided,which will damage the structure.