scholarly journals Temperature-stress coupling mechanism analysis of one-time pouring mass concrete

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1615-1621 ◽  
Author(s):  
Ben-Gao Yang ◽  
Peng He ◽  
Gao-You Peng ◽  
Tong Lu
Keyword(s):  
Stress Field ◽  
Temperature Stress ◽  
Temperature Control ◽  
Damage Control ◽  
Control Measures ◽  
Effect Of Temperature ◽  
Actual Condition ◽  
Coupling Mechanism ◽  
Mass Concrete ◽  
Finite Element Software

Thermal damage control of mass concrete is the key to guarantee the quality of mass projects. Based on several engineering experiences and finite element software ANSYS, the temperature field and stress field of the typical dam section of the Tengzigou hydropower station in Sichuan province were simulated. Considering the actual materials used, cooling measures, etc., maximum tensile stress and compressive stress at different time points derived from the temperature stress field during the time of concrete maintenance were calculated, and the numerical results showed that strength increment under the given conditions was much less than the actual condition. After the concrete of the dam body of the hydro power station were poured, there was no significant temperature stress crack appeared through a long-term observation, and the project condition was in tune with the calculated expectation. The above research results are valuable to further prediction of concrete temperature in different periods, the pre-study of the effect of temperature control measures, and these could offer guidance of the adjustment of temperature control measures in the case of abnormal conditions.

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.

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.

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.

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.

scholarly journals Study on Optimization of Temperature Control Measures for Structure Concrete of Arc Dam

2021 ◽  
Author(s):  
Lei Zhang ◽  
Xiaofang Ma ◽  
Heng Zhao ◽  
Lei Zheng ◽  
Shouxun Ma
Keyword(s):  
Phase I ◽  
Temperature Stress ◽  
Temperature Control ◽  
Simulation Analysis ◽  
Complex Structure ◽  
Arch Dam ◽  
Control Measures ◽  
3D Fem ◽  
Water Pipes ◽  
Cooling Temperature

As the gate pier bracket of an arch dam are of complex structure which is characterized by use of high-grade concrete and more cement, higher adiabatic temperature rise, it is rather difficult to control temperature and vulnerable for cracking, and the cracks would absolutely affect the integrity, endurance and safety of pier gate bracket. It is necessary to take reasonable temperature control measures to reduce temperature stress during the construction and prevent cracking. This paper takes the gate pier bracket at the middle-hole dam section to perform simulation analysis of temperature field and stress field under different temperature control measures by 3D FEM. It proves that such measures as densifying water pipes, improving Phase I target cooling temperature appropriately, reducing Phase I cooling temperature falling variation and keeping insulation in low-temperature season can help reduce temperature stress and prevent cracking with good results.

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 Effect of Hydration Heat Inhibitor on Thermal Stress of Hydraulic Structures with Different Thicknesses

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Wenqiang Xu ◽  
Sheng Qiang ◽  
Zhengkai Hu ◽  
Bingyong Ding ◽  
Bingyong Yang
Keyword(s):  
Thermal Stress ◽  
Stress Field ◽  
Tensile Stress ◽  
Temperature Control ◽  
Hydration Heat ◽  
Control Measures ◽  
Hydraulic Structures ◽  
Hydration Reaction ◽  
Early Hydration ◽  
External Temperature

Concrete hydration heat inhibitor can inhibit the early hydration reaction of concrete and reduce the initial heat release of concrete. However, there is no in-depth research on the effect of hydration heat inhibitor on hydraulic structures with different thicknesses and constraints. In this paper, numerical simulation is used to study the change of temperature and stress field after adding hydration heat inhibitor by establishing the finite element models of tunnel lining, sluice, and gravity dam. The results show that the effect of the hydration heat inhibitors on reducing the temperature peak is inversely proportional to the thickness of the structure. A formula is put forward to evaluate their relation in this paper. When the thickness of the structure is about 6 m, there is no peak cutting effect. For the stress field, hydration heat inhibitor can greatly reduce the thermal stress of the thin-walled structure and make the structure meet the temperature control requirements; for the medium wall thickness structure, it can reduce the internal tensile stress about 50% and the surface tensile stress about 20%, and other temperature control measures are still needed to ensure that the surface tensile stress of the structure meets the requirements; for hydraulic structures with large volume and thickness, the application effect of the inhibitor has limitations, which can reduce the internal tensile stress about 30%, but the tensile stress in the surface area will increase about 7% due to the increase of the internal and external temperature difference; therefore, other temperature control measures such as arranging cooling water pipe, strengthening surface insulation, and so on are needed to ensure that temperature cracks do not occur. This paper provides references and suggestions for the research and engineering application of hydration heat inhibitor.

Influence of Water Pipe Cooling on Thermal Stresses in Mass Concrete

2011 ◽  
Vol 137 ◽  
pp. 12-15
Author(s):  
Xin Li Bai ◽  
Ze Yu Wu ◽  
Wen Liang Ma ◽  
Dan Fei Wang
Keyword(s):  
Temperature Control ◽  
Thermal Stresses ◽  
Early Period ◽  
Control Measures ◽  
Mass Concrete ◽  
Late Period ◽  
Water Pipe ◽  
Effective Measure ◽  
Influence Of Water ◽  
Water Pipe Cooling

Temperature field and stress field of a concrete slab in a ship lock chamber are calculated, considering the influence of layered casting. And the influence of water pipe cooling at the early period of constructing, and at the period after constructing, sunshade, pre-cooled concrete etc are taken into account. The expression of finite difference method considering the effect of water pipe cooling is deducted for temperature analysis. Thermal stress calculation results show that the water pipe cooling at the mid-late period is a comparatively effective measure to reduce tensile stress of chamber mass concrete. And an effective temperature control measure is recommended in summer casting, which is that: sunshade + pre-cooled concrete + water pipe cooling (both at early period and at mid-late period). Mid-late period water pipe cooling must last for three months. Combined with other temperature control measures such as summer cover maintenance, winter cover preservation etc, the concrete cracks can be reduced, and the occurrence of large area run through cracks can be avoided.

Based on MIDAS/CIVIL the Anchorage of Mass Concrete Temperature Field and Stress Field Simulation Analysis

2013 ◽  
Vol 724-725 ◽  
pp. 1482-1488
Author(s):  
Ming Ru Zhou ◽  
Qiong Fei Shen ◽  
Zhao Ning Zhang ◽  
Hong Sheng Li ◽  
Zhong Yu Guo ◽  
...  
Keyword(s):  
Temperature Field ◽  
Stress Field ◽  
Heat Conduction Equation ◽  
Simulation Analysis ◽  
Yellow River ◽  
Time Interval ◽  
Mass Concrete ◽  
Finite Element Software ◽  
Cooling Method ◽  
Concrete Temperature

Based on the foundation of heat conduction equation, this paper analyses the Yellow River bridge liujiaxia anchorage of mass concrete temperature field and stress field in the natural cooling and stratified pouring time interval for 7 days to circumstances with the MIDAS/CIVIL finite element software. The results show that the interval 7 days stratified pouring and natural cooling method, can't meet the requirements of concrete anti-crack.

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