Study On Mechanical Characteristics And Field Monitoring Of Calabash Shaped Anchorage Support Structure Of Long Span Suspension Bridge

Firstly,this paper introduce the development history of diaphragm wall,from rectangle foundation pit to circular foundation pit,further extended to "uncertain" type foundation pit and"gourd shaped" foundation pit.By describing a series of advantages and disadvantages of"gourd shaped" foundation pit to prove it is necessary to study this type of project,then,from the monitoring data and design theory of circular diaphragm wall and extending to "gourd shaped" diaphragm wall,the research status and existing problems of diaphragm wall are expounded;According to the characteristics of "calabash shaped" diaphragm wall,the stress characteristics of two directions are analyzed,and the bending differential equation of cylindrical shell based on axisymmetric condition is put forward,and the bilateral spring model is introduced;The basic equation of axisymmetric plane finite element is introduced after considering the model of annular lining and soil spring on both sides of the structure;Taking the Dongting Lake bridge project of Da Yue expressway as the background,combining the geological prospecting data and related engineering experience,the formation data are sorted out,and the numerical results are obtained after the reasonable working condition calculation;On the basis of the existing engineering experience,combining with the force and deformation characteristics of "gourd shaped" diaphragm wall,the monitoring content,monitoring steps,implementation principles and layout scheme of the diaphragm wall are formulated,then according to the design calculation and construction process of the actual situation of construction monitoring and control index,the information construction means monitoring the entire process of tracking and monitoring "gourd shaped wall excavation,through the information transmission,processing and analysis,the construction instructions are immediately sent back to the construction site;Data extraction and integration of the monitoring data of daily and weekly,according to the requirement analysis of plot and contrast with the numerical results of axisymmetric method validation has reached the purpose of rationality,so as to provide a reference for future similar projects.The main conclusions of this paper are as follows:(1)The structure of gourd shape effectively reduces the radius of the single circle,and can improve the stress characteristics of the retaining structure of the foundation pit.(2)The radial displacement of the gourd shaped diaphragm wall increases with the increase of excavation depth.The maximum value appears in the depth 20m-30m range,and the displacement deformation curve of the foundation pit presents a "S" shape change rule.(3)The rule of excavation depth and meridional stress variation is obtained.According to the above analysis,it is indicated that improper operation or environmental causes during construction will lead to sudden change of radial stress.(4)Through numerical simulation analysis,the variation rule of radial displacement of diaphragm wall is obtained,which is compared with the measured data.It shows that the variation regularity of the bending moment of the diaphragm wall is in good agreement with the actual results.