Seasonal temperature and stress distributions in concrete gravity dams. Part 1: modelling

1993 ◽  
Vol 20 (6) ◽  
pp. 999-1017 ◽  
Author(s):  
P. Léger ◽  
J. Venturelli ◽  
S. S. Bhattacharjee
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Thermal Response ◽  
Companion Paper ◽  
Seasonal Temperature ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Temperature Variations ◽  
Concrete Gravity Dams ◽  
Northern Regions

Seasonal thermal stresses have been found to contribute significantly to the long-term degradation of strength and stiffness of concrete dams located in northern regions. Temperature variations and the associated thermal stress and strain must be evaluated to define the initial loading conditions for safety analyses and develop defensive measures to ensure the durability of the exposed surfaces. This paper presents a finite element modelling procedure to determine the thermal response of concrete gravity dams. Heat transfer and structural analysis models of a typical dam–foundation–reservoir system are developed. The reservoir, foundation, and air temperature variations, as well as solar radiation, are evaluated from data collected from different sources. The rate of convergence of the numerical solution is examined, and a methodology to identify the critical temperature states and to compute the related stresses is presented. The results of extensive parametric analyses describing the thermal behaviour of concrete gravity dams located in northern regions are presented in a companion paper. Key words: gravity dams, thermal analysis, finite element method.

Seasonal temperature and stress distributions in concrete gravity dams. Part 2: behaviour

1993 ◽  
Vol 20 (6) ◽  
pp. 1018-1029 ◽  
Author(s):  
P. Léger ◽  
J. Venturelli ◽  
S. S. Bhattacharjee
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Thermal Stresses ◽  
Thermal Response ◽  
Structural Safety ◽  
Seasonal Temperature ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Frost Penetration ◽  
Parametric Analyses

The thermal response of a typical dam–foundation–reservoir system, using the methodology described in part 1, is presented. Extensive parametric analyses are performed to determine the relative influence, on the thermal and stress–strain responses of the system, due to (i) the geometrical, thermal, and mechanical properties of the dam, (ii) the reservoir, foundation, and air temperature distributions, and (iii) the heat supply from solar radiation. Temperature states to define critical stress conditions for structural safety analyses are determined. Significant thermal stresses occur in the vicinity of the exposed surface of the dam, with a typical depth of frost penetration of about 6 m. The parameters that affect the surface stresses most are the air temperature distribution and the height of the dam, while for frost penetration they are the solar radiation, convection coefficient, and conduction coefficient. Key words: gravity dams, thermal analysis, finite element method.

scholarly journals Modeling of Hydraulic Fracture of Concrete Gravity Dams by Stress-Seepage-Damage Coupling Model

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Sha Sha ◽  
Guoxin Zhang
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Hydraulic Fracture ◽  
Carrying Capacity ◽  
Damage Model ◽  
Coupling Model ◽  
Propagation Path ◽  
Concrete Dams ◽  
Gravity Dams ◽  
Concrete Gravity Dams

High-pressure hydraulic fracture (HF) is an important part of the safety assessment of high concrete dams. A stress-seepage-damage coupling model based on the finite element method is presented and first applied in HF in concrete dams. The coupling model has the following characteristics: (1) the strain softening behavior of fracture process zone in concrete is considered; (2) the mesh-dependent hardening technique is adopted so that the fracture energy dissipation is not affected by the finite element mesh size; (3) four coupling processes during hydraulic fracture are considered. By the damage model, the crack propagation processes of a 1 : 40 scaled model dam and Koyna dam are simulated. The results are in agreement with experimental and other numerical results, indicating that the damage model can effectively predict the carrying capacity and the crack trajectory of concrete gravity dams. Subsequently, the crack propagation processes of Koyna dam using three notches of different initial lengths are simulated by the damage model and the coupling model. And the influence of HF on the crack propagation path and carrying capacity is studied. The results reveal that HF has a significant influence on the global response of the dam.

Seismic Analysis of Concrete Gravity Dams: Nonlinear Fracture Mechanics Models and Size-Scale Effects

2011 ◽  
Vol 82 ◽  
pp. 374-379 ◽  
Author(s):  
Marco Paggi ◽  
Giuseppe Ferro ◽  
Franco Braga
Keyword(s):  
Crack Propagation ◽  
Seismic Analysis ◽  
Scale Effects ◽  
Constitutive Law ◽  
Dam Failure ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Size Scale ◽  
Concrete Gravity Dams ◽  
Nonlinear Dynamic Problem

The phenomenon of interface crack propagation in concrete gravity dams underseismic loading is herein addressed. This problem is particularly important from the engineeringpoint of view. In fact, besides Mixed-Mode crack growth in concrete, dam failure is oftenthe result of crack propagation along the rock-concrete interface at the dam foundation. Toanalyze such a problem, the generalized interface constitutive law recently proposed by the¯rst author is used to proper modelling the phenomenon of crack closing and reopening at theinterface. A damage variable is also introduced in the cohesive zone formulation in order topredict crack propagation under repeated loadings. Special attention is given to the complexityresulting from the solution of the nonlinear dynamic problem and to the choice of the interfaceconstitutive parameters, taking into account the important size-scale e®ects observed in thesecyclopic structures. Numerical examples will show the capabilities of the proposed approachwhen applied to concrete gravity dams.

Thermal protection of concrete dams subjected to freeze–thaw cycles

1995 ◽  
Vol 22 (3) ◽  
pp. 588-602 ◽  
Author(s):  
P. Léger ◽  
M. Côté ◽  
R. Tinawi
Keyword(s):  
Finite Element ◽  
Thermal Protection ◽  
Seasonal Temperature ◽  
Concrete Dams ◽  
Freeze Thaw ◽  
Stiffness Properties ◽  
Protection Systems ◽  
Northern Regions ◽  
Strength And Stiffness

Concrete dams located in northern regions are subjected to severe cyclic seasonal temperature variations, which may contribute significantly to the deterioration of the exposed faces and the long-term degradation of strength and stiffness properties. This paper presents a comparative study of thermal protection methods that might be used to improve the durability of concrete dams subjected to freeze–thaw cycles. First, the thermal, structural, and physical processes that affect the dam's resistance to freeze–thaw cycles are discussed. The thermal durability of existing northern concrete dams is then reviewed. Three thermal protection schemes are presented: (i) insulation membranes applied directly to the concrete facings, (ii) insulation membranes with air spaces for drainage or visual inspection, and (iii) insulation made of granular material. Two-dimensional thermomechanical finite element analyses of a typical gravity dam located in Quebec are then carried out to assess the performance of thermal protection systems using different configurations of insulating materials and exposure conditions, and to develop appropriate design criteria. Key words: concrete dams, thermal analysis, insulation, finite element method.

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