Study On The Global And Local Stability Of Rectangular Thin-walled Aqueduct

Water is the source of life for any life on the earth.With the continuous development of economy,people's demand for water resources is not increasing.In some areas of our country,there are insufficient water supply or uneven distribution of water resources.In order to solve this series of problems,a large number of water transmission projects have emerged,among which aqueduct is one of the large-scale hydraulic structures.However,with the wide application of aqueduct,we gradually find that the investment,construction progress and even use value of aqueduct project are affected by various aspects,the more typical one is the rationality and safety of the structural setting in aqueduct design.Therefore,more and more attention has been paid to the stability analysis of aqueduct structure.In this paper,the overall stability of aqueduct structure,the local stability of aqueduct structure and the stability of the lower supporting structure(pier structure)of aqueduct are analyzed and studied.In addition to using theoretical formula for calculation and analysis,the computer program is also used for calculation and drill to verify the rationality of the results,and the analysis model and finite element calculation model of aqueduct are established,and the actual project,the aqueduct in the middle of Yunnan Province,is taken as the research object for analysis and calculation.The main contents are as follows:(1)Overall stability analysisIn the overall stability analysis of aqueduct structure,the geometrical properties of aqueduct section are derived,the balance equations of bending moment and torque are established by using the principle of energy variation,and the analytical expressions of the critical bending moment of lateral torsional buckling of rectangular thin shell aqueduct are obtained by Galerkin method and Rayleigh Ritz method.Taking the Adou Village aqueduct as an engineering application object,the critical moment of lateral torsional buckling of aqueduct structure is calculated.The results show that the overall failure of the trough structure does not occur in the Adou Village aqueduct.The factors affecting the critical bending moment(aqueduct span,upper flange width,and aqueduct wall thickness)of torsional buckling of the aqueduct are analyzed.The calculation results show that the variation of the aqueduct span has the greatest influence on the lateral torsional buckling of the aqueduct;the changes in the width of the upper flange of the aqueduct and the thickness of the aqueduct within the normal range have little effect on the critical stress of the aqueduct side torsional buckling.(2)Local stability analysisDerived the theoretical formula of the semi-analytical finite strip element method,established the basic equations of the semi-analytical finite strip element method,and developed a special computer program(WDFX)for the stability analysis of thin shell structures;a large-scale structural analysis software ANSYS is used to establish a large-scale A finite element model of the aqueduct body structure,and the eigenvalues of buckling mode is obtained.Through the calculation,the analysis results of the local stability of the aqueduct are obtained.It is found that the relative error of the two results is less than 3%,and the results are within a reasonable range.This shows that the semi-analytical finite strip element method(WDFX program)mentioned in this paper meets the accuracy requirements of engineering applications;at the same time,it can be judged that the local failure of the Adou Village aqueduct will not occur.(3)Structural stability analysis of aqueduct pierMost of the aqueduct piers use hollow thin-walled piers,which belongs to the instability problem of bending members.In this paper,Newton iteration method and finite element method are used to analyze the stability of the aqueduct pier structure.Taking the Adou Village aqueduct as an example,the analysis and calculation were performed.The eigenvalue of buckling mode obtained by Newton iteration method was 538.76 MPa,and the eigenvalue of buckling mode obtained by ANSYS software was 541.09 MPa.The results of the two calculations are very close(the relative error is small)and both are within a reasonable range.Compared with the load of the bridge pier under the operating condition of full aqueduct water load at Adou Village Aqueduct,it can be known that the structure will not fail.