Force Analysis for Concrete Arch Dam Structure of Banjiang Reservoir

Abstract

Concrete arch dam is the main structure of water conservancy projects,which have the advantages of a artistic shape of structure and good mechanical properties, and it has been widely used in water conservancy projects. Banjiang Reservoir is located in Zijiang River two tributaries of Dongkou County, Hunan Province, which is a reservoir to generate electricity, combined with irrigation water resources and hydropower engineering. This article gives the stress and deformation distribution during construction and operation which has done the simulation analysis for concrete arch dam structure of Banjiang Reservoir using the finite element method. The results show that Concrete Arch Dam Structure of Banjiang Reservoir satisfy the design requirements. Using concrete arch dam scheme of Banjiang Reservoir River is reasonable. Basically, circumferential stress of arch dam upstream face is compressive stress. Furthermore, the arch′s first principal stress which is small can meet the strength requirements, so the structure is safe and reliable. Keywords-Banjiang reservoir; Concrete arch dam; Finite element method; Stress distribution; Simulation analysis. I. ENGINEERING SITUATION Banjiang Reservoir is located in Zijiang River two tributaries of Dongkou County, Hunan Province, which is a reservoir to generate electricity, combined with irrigation water resources and hydropower engineering[1]. The distance is 12km from the site of dam to country and the controllable area of upstream of dam site is 36.4 m. Normally, the reservoir is 39 m. The flood level of design is 42.5 m. and corresponding downstream water level is 15.9 m. Check flood level is 43.1 m, and corresponding downstream water level is 16.4 m. Hub engineering is composed of dams, factories, irrigation and power diversion canal, flood discharge pipe and other buildings[2]. The dam is concrete singles arch dam which is scheduled circle and fixed outer radius[3]. The maximum height is 44.7 m, and the dam bottom thickness is 15 m. Arch section ratio of thickness to height is 0.37, the maximum central angle 3 4 119   , the minimum central angle  21 . The concrete strength of arch class is C20. II. CALCULATION MODEL A Model Parameters Concrete arch dam structure of banjiang reservoir uses concrete strength grade of C20, elastic modulus 5 . 25 1  E GPa, poisson ratio 167 . 0 1   [4],bulk density 24 1   kN/m .The rock of dam is quartz sandstone, and dam's riverbed hasn't tomographic. The elastic modulus of rock is 2 E =20GPa[5], poisson ratio 28 . 0 2   . B Model Element Concrete arch dam and bedrock structure model uses isoparametric block element which has 8-node[6]. The element is applied to three-dimensional model of the entity structure, have properties of plasticity, creep, swelling, stress stiffening, large deformation and large strain. The element has eight nodes and each node has three translational degrees of freedom[7-8] . C Model Size The size of the entire calculation model is that it takes 65m along the direction of the river, 55m the direction of across the river, 33.6m the vertical direction. The simulation range of model is 65m × 55m × 33.6m(along the river×across the river×the vertical direction) . The element division of arch and rock is shown in Fig .1. International Conference on Mechatronics, Electronic, Industrial and Control Engineering (MEIC 2014) © 2014. The authors Published by Atlantis Press 1207 Figure 1. Arch and bedrock FEM division D Calculation Condition Considering the mechanical characteristics of arch structure during operation[9],the following five cases are taken into account mainly: case1(structural weight),case2(structural weight and normal water level),case3(structural weight, design flood level and tail water level),case4(structural weight, checking flood level and tail water level),case5(structural weight, design flood level, tail water level and earthquake). III. ARCH STRUCTURE ANALYSIS A Stress Analysis The first principal stress and vertical stress of arch various case contour map see Fig .2 to Fig .11. Figure 2. Cloud map of arch’s first principal stress under case 1(Pa) Figure 3. Cloud map of arch’s vertical stress under case 1(Pa) Figure 4. Cloud map of arch’s first principal stress under case 2(Pa) Figure 5. Cloud map of arch’s vertical stress under case 2(Pa)