Sensitivity Analysis Of Eccentricity And Lining Thickness Of Elliptical Section Gate Wells

The gate well structure is an important permanent structure of the pumped storage power plant diversion system,and its structural stability is directly related to the normal operation of the diversion system,so it is particularly important to ensure the structural safety of the gate well.Compared with the rectangular sectional gate structure,the elliptical sectional gate has good force characteristics and high structural safety,but there is no standardized standard for the design parameters of the gate structure.In this paper,a diversion accident gate well of a pumped storage power plant is used as a research object to conduct sensitivity analysis on the mechanical characteristics of the elliptical section gate well and optimize the gate well design scheme.The research content and results are as follows:(1)A finite element model of an elliptical section gate well,including the wellbore,wellbore seat,and surrounding rock,was constructed using ANSYS,a large general-purpose finite element analysis software.On this basis,the stress analysis of the gate cavity was performed,and the deformation and stress distribution law of the gate cavity were studied.The results show that the stress and deformation of the elliptical section gate shaft are symmetrically distributed,which is consistent with the general underground shaft stress and deformation law and can be used for further analysis.(2)Elliptical section gate well eccentricity,well lining thickness,and well seat lining thickness were selected as the influencing factors,and the maximum deformation and stress of the well and the well seat were taken as the test indexes,and sensitivity analysis was conducted using single-factor analysis for elliptical section gate wells under maintenance and normal operation conditions to obtain the variation trend between each structural parameter and the test index.The results show that all the influencing factors have some influence on the test index,among which the thickness of the well seat liner has the highest sensitivity to the maximum deformation and stress of the elliptical section gate well.(3)The elliptical section gate well eccentricity,well lining thickness and well seat lining thickness were selected as the influencing factors,and the maximum deformation and stress of the well and the well seat were taken as the test indexes,and a multi-factor sensitivity analysis scheme was established by the orthogonal test method,and the sensitivity analysis of the test results was conducted by the extreme difference analysis method and the analysis of variance method.The results show that the thickness of the well seat liner is the most sensitive factor for each test index under both maintenance and normal operating conditions,and is the primary factor influencing the mechanical properties of elliptical section gate wells.(4)Based on the results of sensitivity analysis,the optimal design of elliptical section gate wells was carried out with the parameters of e=0.6 for the eccentricity,B1=1.2m for the shaft lining thickness and B2=1.8m for the seat lining thickness,and the numerical simulation results of the original scheme and the optimized scheme were compared and analyzed.The results show that the maximum deformation and stress of the optimized solution are smaller,better,and safer than the original solution,demonstrating the accuracy of the sensitivity analysis.