A New Method for Improving the Stress Status of the Dam

2013 ◽  
Vol 444-445 ◽  
pp. 849-853
Author(s):  
Jian Hua Cui ◽  
Yong Feng Qi ◽  
Jie Su
Keyword(s):  
Temperature Control ◽  
Cooling Water ◽  
Control Measures ◽  
Sensitivity Analyses ◽  
Mass Concrete ◽  
Water Cooling ◽  
Concrete Gravity Dam ◽  
3D Fem ◽  
Construction Period ◽  
Operation Period

Under the action of annual change and sudden drop of air temperature, thermal induced cracking will occur in concrete dam during the operation period. For exploring the temperature control measures for crack prevention, taking a concrete gravity dam section as the research object, sensitivity analyses to the factors which affecting the water-cooling effect are conducted with 3D FEM, some significant suggestions for the water cooling are presented. The results show that, the stresses of the dam surface will decrease to a certain extent after water cooling in the operation period using the cooling water pipe which embedded during construction period, and the cracking risk of the dam will reduce. The study provides a new train of thought for the temperature control and crack prevention of the mass concrete during the operation period.

Contact Analysis on the Longitudinal Joint of Gravity Dam

2011 ◽  
Vol 250-253 ◽  
pp. 2931-2934 ◽  
Author(s):  
Jian Hua Cui ◽  
Han Jiang Xiao ◽  
Liang Shan
Keyword(s):  
Cooling Water ◽  
Present Condition ◽  
Gravity Dam ◽  
Concrete Gravity Dam ◽  
Nonlinear Fem ◽  
Water Load ◽  
Construction Period ◽  
Operation Period ◽  
Longitudinal Joint ◽  
Temperature Water

In order to understand the contact condition of longitudinal joint of gravity dam and its influence on dam body stress, taking a concrete gravity dam section as the research object, the numerical simulations with 3D nonlinear FEM is carried out through the simulating of the construction period, the grouting process and the operation period. It shows that the opening of the longitudinal joint varies with many kinds of factors, such as the year temperature, water cooling, water load on the upstream surface, the construction process and so on. Under the present condition, secondary grouting to the longitudinal joint may not be carried temporarily. The computation results are basically in agreement with the prototype monitoring data.

Temperature Control Measures Optimization of RCC Gravity Dam

2012 ◽  
Vol 226-228 ◽  
pp. 1153-1156 ◽  
Author(s):  
Shu Ping Huang ◽  
Jian Yun Fu ◽  
Yan Cai Li
Keyword(s):  
Temperature Control ◽  
Simulation Analysis ◽  
Control Measure ◽  
Control Measures ◽  
Gravity Dam ◽  
Mass Concrete ◽  
Dam Construction ◽  
Construction Technology ◽  
3D Fem ◽  
Single Temperature

With the continuous development of dam construction technology, the RCC dam becomes one of the most popular types of dam in the world with its unique advantages. Temperature control measures research is one of the key issues of design and construction of mass concrete structures. How to choose the proper temperature control measures to prevent concrete cracks becomes the important problem of dam construction technology. In a RCC gravity dam, the climate environment is so severe that a single temperature control measure can’t meet the requirements of temperature control and crack prevention. In this paper, 3D FEM simulation analysis is used to calculate temperature field and thermal creep stress field during the whole construction process. According to the simulation results, the temperature control measures design of the dam has been comprehensively evaluated and the temperature control measures of this project have been put forward.

Temperature Cracks Controlling Technology for the Mass Concrete in Solid Sections of Lower Pylon Column

2013 ◽  
Vol 467 ◽  
pp. 262-269
Author(s):  
Fu Liang Gao ◽  
Yan Wei Fang
Keyword(s):  
Temperature Control ◽  
Thermal Stresses ◽  
Cooling Water ◽  
Control Measures ◽  
Mass Concrete ◽  
Removal Time ◽  
Control Scheme ◽  
Section Size ◽  
Circulating Cooling Water ◽  
Binder Ratio

According to the case that mass concrete in solid sections of lower pylon column of Jiashao Bridge was easy to crack in construction because of the bigger section size, larger content of cementitious material and lower water binder ratio, the temperature and thermal stresses distribution of mass concrete was simulated and temperature control scheme was adjusted constantly based on the results of field temperature monitoring. Through taking some temperature control measures such as applying circulating cooling water and prolonging the time appropriately, thermal insulation and moisture retention curing, extending the form removal time and controlling the quality of concrete, harmful cracks did not appear in solid sections of lower pylon column of Jiashao Bridge and anticipated temperature control requirements were achieved.

Temperature Control Measures' Intelligent Optimization for Quasi-Mass Concrete Structure

2013 ◽  
Vol 357-360 ◽  
pp. 884-887
Author(s):  
Yao Ying Huang ◽  
Yue Mei Ding ◽  
Xiao Man Lv ◽  
Teng Fei Tang
Keyword(s):  
Neural Network ◽  
Temperature Control ◽  
Growth Curve ◽  
Control Measures ◽  
Tension Stress ◽  
Mass Concrete ◽  
Water Cooling ◽  
Optimal Temperature ◽  
Tension Strength ◽  
Temperature Water

Related to temperature control measures and material parameters, crack prevention by temperature control in quasi-mass concrete is an optimization problem including multiple complicated factors. This study tries to do some optimization of temperature control measures in the given concrete thermodynamics parameters circumstance. The quasi-mass concrete structure’s minimum value of the relationship between principal tensile stress duration curves of internal and surface and the tensile strength growth curve are taken as the input, and the gate pier surface heat preservation effect, pouring temperature, water cooling temperature, water cooling time are taken as the output, we establish the optimal temperature control measures by the neural network model. Applying the uniform design principle to combine the temperature control parameters, and using the finite element method to analyze the temperature field and creep stress field in the quasi-mass concrete structure containing cooling water pipes, we obtain the samples, for training the network, to describe the nonlinear relationship between the principal tension stress duration curve and the tension strength growth curve and the different temperature control measures. After inputting the fitting minimum value of relationship between the principal tension stress duration curve and the tension strength growth curve to the trained network, the system is able to automatically select the optimal temperature control measures for crack prevention. The example shows that the proposed optimal neural network model for temperature control measures is feasible.

scholarly journals Temperature Control Measures and Temperature Stress of Mass Concrete during Construction Period in High-Altitude Regions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Zhenhong Wang ◽  
Li Tao ◽  
Yi Liu ◽  
Jiang Yunhui
Keyword(s):  
High Altitude ◽  
Temperature Stress ◽  
Temperature Control ◽  
Lower Layer ◽  
Temperature Drop ◽  
Control Measures ◽  
Mass Concrete ◽  
Prevention Measures ◽  
Concrete Gravity Dam ◽  
Climate Conditions

The focus on the development of China’s vast hydropower resources has shifted to Tibet and other plateau regions. These areas are high-altitude regions whose basic climatic characteristics are as follows: dry climate, significant differences in daily temperature, and strong solar radiation. If a dam is built under such special climate conditions, specific and strict temperature control and crack prevention measures should be taken. Therefore, this study explores the temperature control standards, as well as temperature control and crack prevention measures, for concrete in high-altitude regions using three-dimensional finite element methods and based on the concrete gravity dam in Tibet in combination with the characteristics of material properties that are disadvantageous to temperature control and crack prevention. The temperature drop process can be optimized in time, and the temperature drop rate can be controlled to prevent excessive scale and temperature drop rates. Moreover, the temperature gradient can be spatially optimized, and thus, the differences in foundation temperatures, upper- and lower-layer temperatures, and internal and external temperatures can also be reduced. The research shows that the recommended temperature control and crack prevention measures can effectively reduce temperature stress. This study has a significant value as a reference for similar projects in high-altitude regions.

Temperature Control Measures and Feedback Analysis in Rapid Construction of Guandi RCC Dam

2012 ◽  
Vol 594-597 ◽  
pp. 1979-1982
Author(s):  
Wei Zhou ◽  
Xiang Yang Jing ◽  
Xing Hong Liu
Keyword(s):  
Temperature Control ◽  
Control Method ◽  
Dynamic Control ◽  
Cooling Water ◽  
Control Measures ◽  
Obvious Effect ◽  
Feedback Analysis ◽  
Cooling Water Temperature ◽  
Rcc Dam ◽  
Rapid Construction

Due to the shortcomings of conventional methods, the temperature control in rapid construction of Guandi dam is less effective. Then improved measures are designed and implemented based on the dynamic control method of pipe cooling, which depends on the real-time adjustment of five factors affecting pipe cooling (beginning time of cooling, lasting time of cooling, water temperature, rate of flow and direction of flow). The monitoring and feedback calculation are conducted. It is found that the newly-designed measures have obvious effect, and that there are no harmful cracks in the whole construction of Guandi dam. The conclusion is that it can effectively solve the problem of temperature control and crack prevention of high RCC dam via these measures, and provide some guide and reference to other similar projects.

Study on Crack Prevention Measures of Mass RCC Dams

2013 ◽  
Vol 743 ◽  
pp. 3-8
Author(s):  
Jian Guo Jing ◽  
Min Zhi Liu ◽  
Shao Jun Zeng ◽  
Lin Xu
Keyword(s):  
Temperature Control ◽  
Control Measures ◽  
Simple Construction ◽  
Prevention Measures ◽  
Construction Period ◽  
The Way

Actually, both simple construction and fast construction are advantages of RCC dams. In view of taking strict temperature control measures, those are turned to be disadvantages instead. The way of fast pouring and the measure of controlling the placing temperature are introduced to RCC dams and 6 cases are analyzed separately to explain the effect of their crack prevention. It is concluded that controlling only the last layer placing temperature of concrete lifts can remarkably decrease the stress of working plane concrete during off period. Furthermore, the pouring way of thick lifts and short off period do not deteriorate the temperature and stress but rather has an impressive effect on crack prevention and construction period contraction.

scholarly journals Temperature Control Technology for Construction of Jinsha River Bridge

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hui-Wu Jin ◽  
Guo-An Wang ◽  
Zhan-Ming Chen
Keyword(s):  
Temperature Control ◽  
Temperature Difference ◽  
Cooling Water ◽  
Good Health ◽  
Large Mass ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Jinsha River ◽  
Mixture Ratio ◽  
Concrete Temperature

The key problem of mass concrete temperature control is to effectively control the maximum temperature inside concrete, the temperature difference between inside and outside concrete, and the temperature difference between surface and environment. The size of the main tower cap of No. 3 Jinsha River Bridge is 37 m × 23.5 m × 5.5 m, and the cubic volume of concrete reaches 4782.3 m3, which is poured in two times. In order to ensure construction quality of mass concrete structure, prevent the large mass concrete temperature stress, through the numerical simulation of the temperature control and optimization scheme, by optimizing the mixture ratio design, reducing the temperature of concrete pouring into the mold, cooling water cycling, insulation keeping in good health and a series of measures to effectively achieve the control goal, and eliminating the temperature cracks. The measured data show that the maximum temperature inside concrete, the temperature difference between inside and outside, and the temperature difference between surface and environment are qualified, but the temperature difference control of cooling water inlet and outlet has hysteresis effect, and the temperature difference between inlet and outlet will be greater than 10°C, which should be noticed.

scholarly journals Precise Simulation of Heat-Flow Coupling of Pipe Cooling in Mass Concrete

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5142
Author(s):  
Peng Yu ◽  
Ruiqing Li ◽  
Dapeng Bie ◽  
Xiancai Liu ◽  
Xiaomin Yao ◽  
...  
Keyword(s):  
Heat Flow ◽  
Temperature Gradient ◽  
Temperature Control ◽  
Cooling Water ◽  
Mass Concrete ◽  
Finite Element Software ◽  
Flow Coupling ◽  
Cooling Pipe ◽  
Cooling Effects ◽  
Precise Simulation

For a long time, temperature control and crack prevention of mass concrete is a difficult job in engineering. For temperature control and crack prevention, the most effective and common-used method is to embed cooling pipe in mass concrete. At present, there still exists some challenges in the precise simulation of pipe cooling in mass concrete, which is a complex heat-flow coupling problem. Numerical simulation is faced with the problem of over-simplification and inaccuracy. In this study, precise simulation of heat-flow coupling of pipe cooling in mass concrete is carried out based on finite element software COMSOL Multiphysics 5.4. Simulation results are comprehensively verified with results from theoretical solutions and equivalent algorithms, which prove the correctness and feasibility of precise simulation. Compared with an equivalent algorithm, precise simulation of pipe cooling in mass concrete can characterize the sharp temperature gradient around cooling pipe and the temperature rise of cooling water along pipeline more realistically. In addition, the cooling effects and local temperature gradient under different water flow (0.60 m3/h, 1.20 m3/h, and 1.80 m3/h) and water temperature (5 °C, 10 °C, and 15 °C) are comprehensively studied and related engineering suggestions are given.

The Whole Process Simulation and Research on Temperature Field and Thermal Stress for Large Sluice Pier

2010 ◽  
Vol 163-167 ◽  
pp. 259-263 ◽  
Author(s):  
Hai Bo Wang ◽  
Sheng Qiang ◽  
Zhen Yang Zhu ◽  
Zhi Qiang Xie
Keyword(s):  
Temperature Field ◽  
Stress Field ◽  
Control Measures ◽  
Internal Cooling ◽  
3D Fem ◽  
Construction Period ◽  
Whole Process ◽  
Cooling Pipe ◽  
Field Environment ◽  
Temperature Filed

Based on the real construction process and field environment of large sluice pier for Caojie Project, considering the factors of surface insulation, internal cooling, the strength of the foundation and environmental climate, the basic theories of temperature field and stress field of concrete and 3D FEM combining with cooling pipe discrete model and iteration method are used to carry out the study of cracking mechanism. According to the 3D dynamic simulation of the temperature filed and stress field for the pier, reasonable temperature control measures are put forward for reference during construction period. The result of the simulation shows that the concept of the exterior thermal insulation and interior pipe cooling measures are of great useful in practice, and the methods should have great reference signification in future.

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