Optimization Of Arch Dam Shape Of Upper Open Channel

Arch dam is an important type of dam in water conservancy construction.Because arch dam is a spatial shell structure with complex boundary conditions,geometric shapes and stress states,it is difficult to find the shape of arch dam with superior economy and safety.Therefore,the method of dam stress analysis and arch dam shape optimization design plays an important role in the design and construction of arch dam.At present,the strength and safety of arch dam are mainly measured by the calculation results of trial-load method and FEM.Trial-load method is widely used at home and abroad.It regards arch dam as a series of arch rings and straight beams.The load distribution of arch system and beam system can be obtained by solving algebraic equations with consistent node displacement,advantage is less calculation data,fast and intuitive.However,the interaction between arch dam and foundation cannot be considered in the conventional method,so the calculation results are distorted.FEM to the foundation and dam body of finite discrete units,and with nodes are interconnected,established between nodes displacement and force balance equation,and the nodal displacement unit stress is obtained,the calculation of its function was stronger than arches points load method,can consider to complex foundation,the difficult to deal with problems such as large orifice,the installment construction,is a practical and effective method,but calculation is too big,must use the computer to complete,due to the finite element calculation results for stress rather than internal force,not convenient for engineers to use.On the basis of studying the basic theory of arch dam,this paper deduces the method of load sharing of arch beam with four directions(Radial,tangential,torsional and bending)of displacement coordination.This method can fully consider the shear and torsion effect between different arch and beam,different arch ring and the interaction between beam end and foundation.Combined with the laizi river arch dam in guizhou province,the stress calculation is carried out by using the four-way coordination method,Trial-load method and FEM respectively.The calculation results show that the four-way coordination method and Trial-load method sharing method have the same calculation speed,but the four-way coordination result is closer to FEM result.The upper part of laizi river arch dam is open and the lower part is narrow,make the stress condition than conventional arch dam is more complex,result in bodily form design is very difficult.In order to save investment,the four-way coordination theory and the minimum investment(minimum volume of concrete)were used to optimize the shape of the arch dam.The automatic optimization of the arch dam was realized on the ANSYS platform.Under the condition of meeting the standard stress control conditions,the final optimization plan was 23% less than the concrete volume of the feasibility study plan,greatly reducing the volume of the dam body.Through the above research,the four-way coordination method is more rigorous than the arch beam loading method,and more acceptable to engineers than the finite element method,which is worth popularizing.The stress analysis of the open top arch dam focuses on the middle interface,where the torsion effect is obvious,which cannot be analyzed by the conventional arch beam analysis method.The upper arch of the arch dam transfers more shear force and torque to the beam,which should be paid attention to in the design.