scholarly journals The problem of temperature cracking in concrete gravity dams

Vestnik MGSU ◽  
2020 ◽  
pp. 380-398
Author(s):  
Nikolay A. Aniskin ◽  
Nguyen Trong Chuc

Introduction. The concreting of solid structures, such as concrete dams, bridge constructions, foundations of buildings and structures, is accompanied by exothermic heating, caused by cement hydration. Heat, emitted by mass concrete blocks, slowly leaves constructions. A substantial temperature difference frequently arises between the solid concrete centre and its surface. If this temperature difference reaches a critical value, thermal cracking occurs, which destroys structural continuity. Temperature problems and those associated with thermal stress state should be resolved to pre-assess and prevent potential cracking. This problem has enjoyed the attention of specialists, and it has been the subject of numerous research projects. Materials and methods. The overview is based on the information about implemented research projects focused on the thermal cracking of mass concrete dams and its prevention. Computer modeling techniques were applied to develop a mathematical model capable of projecting and assessing the potential cracking of mass concrete. Results. The co-authors have compiled an overview of advanced approaches to the assessment of potential thermal crack formation, contemporary problem-solving methods and selected research findings obtained using the finite element method. The co-authors offer a thermal behaviour/thermal stress state projection methodology for solid concrete, as well as a thermal crack formation assessment methodology. Conclusions. The thermal cracking problem has not been solved yet. The proposed methodology and a projection-oriented numerical model can be used as a reference by civil engineers in the process of designing and constructing concrete gravity dams. It may help to reduce cracking probability caused by heat evolution in cement.

2020 ◽  
Vol 13 (2) ◽  
pp. 64-71
Author(s):  
Vladimir Starcev ◽  
S. Nikolenko ◽  
Svetlana Sazonova

The modeling of the thermal stress state of the foundation slab of the building of a general educational institution is considered. The performed calculations took into account the occurrence of stresses as a result of heating of the concrete mass during cement hydration. To simulate the thermal stress state, the specialized Midas Fea software package is used. At control points, diagrams of changes in temperatures, stresses, and crack formation coefficients depending on the periods of curing are obtained. The isopoles of temperature distribution and crack formation coefficients over the volume of the studied array were obtained. Measures have been developed to improve the operational properties of concrete, including engineering and technical recommendations to reduce the negative impact of temperature differences on the manufacturing process of concrete mixtures and foundations.


Vestnik MGSU ◽  
2021 ◽  
pp. 1483-1492
Author(s):  
Nikolai A. Aniskin ◽  
Nguyen Trong Chuc

Introduction. The contact area of concrete gravity dams is of vital importance. Substantial temperature gradients and tensile stresses can arise in the process of concrete casting and thermal regime creation; they can cause thermal cracking. The practice of monitoring the construction and operation of concrete gravity dams has identified frequent vertical cracking along and across the dam axis, which can have an adverse impact on structural behaviour. Despite the large number of research works, some of which are mentioned in the work, the extent of influence of the modulus of elasticity in the bed on the thermally stressed state of mass concrete has yet to be fully resolved. The purpose of the research is to enhance the insight into the stress-strain state arising in the contact area of mass concrete and the bed, depending on its rigidity. Materials and methods. The research was conducted using the numerical finite element method and the MIDAS software package. Results. The influence of bed rigidity on the thermally stressed state arising in the contact area of mass concrete in the process of construction has been analyzed. Several options featuring different ratios between the modulus elasticity of the bed and mass concrete were considered in respect of a mass concrete structure made of vibrated and rolled concretes. Emerging stresses are compared. Mathematical expressions are obtained to project maximum tensile stresses occurring in the contact area. Conclusions. A more rigid bed rises maximum tensile temperature stresses, which increase the risk of thermal cracking. Research results can be used to predict maximum tensile stresses near the contact section of the mass concrete, whose dimensions are close to those of the structure under research.


1986 ◽  
Vol 18 (1) ◽  
pp. 87-92
Author(s):  
A. S. Tsybenko ◽  
B. A. Kuranov ◽  
A. D. Chepurnoi ◽  
V. A. Shaposhnikov ◽  
N. G. Krishchuk

1986 ◽  
Vol 18 (5) ◽  
pp. 692-698
Author(s):  
Ya. S. Podstrigach ◽  
Yu. A. Chernukha ◽  
N. I. Voitovich

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