Abstract
In order to make clear the cracking reasons in arch dam of Xiaowan Hydropower Station during operation period, the approach to combine ANSYS with finite element program COCE-3D is adopted. Firstly, the influence by element type and mesh size for the temperature field simulation result is analyzed. Subsequently, the three typical dam segments cut from Xiaowan arch dam are selected and the relevant finite element model is established; the effect of the measured diurnal air temperature on temperature field and temperature stress of arch dam is analyzed thoroughly. The results indicate that the temperature gradient in mass concrete becomes lower, whereas the affecting depth becomes deeper when the mesh size is too large. Therefore, it is advisable to use smaller size mesh to study the influence of the measured diurnal air temperature on the surface temperature distribution in mass concrete. The temperature of downstream zone in arch dam is significantly affected by air temperature; the changing laws of temperature field and temperature stress with the air temperature are basically consistent, which is sensitive to lower temperature. When the temperature sharply decreased, the temperature stress in the downstream zone is mainly in tensile stress state. The calculated results are basically consistent with the measured results, and the temperature stress induced by the day-night temperature difference is the important reason for the horizontal cracks on the downstream surface. The submodel analysis method is an important alternative approach to study the changing laws of temperature field of arch dam. The research results not only provide an evidence for temperature control and crack prevention of Xiaowan arch dam but also provide a reference for temperature field simulation of similar projects.
Highlights
It is acknowledged that thermal load is one of the important reasons for concrete arch dam cracking, both during construction and operation [1,2,3,4]
Lots of achievements [3] related to thermal stress and temperature cracks of concrete dams mainly are focused on the influence of the diurnal temperature variation during the construction [8, 9], and the annual temperature [10], seasonal temperature variations [4, 11, 12], solar radiation [13, 14], and water temperature variations [1] during the operation. e results show that the cold wave or the diurnal temperature variation will affect the thermal field within a certain range below the concrete surface and lead to the surface cracks [15]
(2) Under the same action of air temperature variation law, values of temperature variation at P1 and P2 were basically consistent with the variation law. (3) e temperature gradient of concrete surface was affected more obviously by the change of diurnal temperature variation in winter
Summary
It is acknowledged that thermal load is one of the important reasons for concrete arch dam cracking, both during construction and operation [1,2,3,4]. Due to the exothermic reactions, a lot of hydration heat cannot be released in time, resulting in the increase of internal temperature gradient and thermal stress, which leads to cracks It is usually controlled by cooling water pipes or lowering concrete pouring temperature. As for the causes of cracks during the operation, Zhu proposed that the fundamental reason was that the influence of nonlinear temperature difference and cold wave was not considered in the calculation of temperature load. He proposed that permanent surface thermal insulation was an effective method to prevent cracks occurring in arch dams during operation [7]. It provides the guideline for temperature control and crack prevention of Xiaowan arch dam and reference for similar projects
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
