Temperature cracks commonly occur during mass concrete construction. Research shows that changes in temperature and peripheral constraints mainly cause crack formation in concrete. Engineers who lack experience often build structures prone to concrete cracks. Dams built in the high-altitude areas of Tibet are examples of such structure. Climatic conditions, such as large temperature variation and strong solar radiation, disrupt temperature control and crack prevention in concrete. In this study, we explored the measures for temperature control and crack prevention that are suitable for concrete structures, especially those built in high-altitude areas with large temperature variation and strong constraint zones. The study was performed in a steep slope dam section and stilling basin in Tibet. The finite element method was used to guide the engineering construction in the area. These methods could be applied to the construction of similar projects in other high-altitude areas. KeywordsHigh altitude, concrete cracks, steep slope dam section, stilling basin, large temperature difference, strong constraint ForewordMass concrete has been extensively used in various infrastructure projects, such as water conservancy and hydropower projects, bridges, ports, and concrete dams. However, crack formation in these infrastructures remains to be a persistent problem.1-3 Since the 1930s, a set of theoretical systems for temperature control and crack prevention has been developed, along with several measures against crack formation in concrete; these measures include improving the crack resistance of concrete, blocking of concrete dams, pipe cooling, and preserving surface heat.4-7 However, no dam at home and abroad is free from crack, and such condition severely affects the durability and safety of structures. Engineering experience indicates that the difficulty in avoiding cracks is due to insufficient understanding of the mechanism of crack formation, the randomness of hydrometeorological conditions, and the failure of material parameters in reflecting actual engineering conditions; in addition, crack formation occurs because of the absence of timely and reasonable measures for temperature control that are tailored to the actual conditions of specific projects. [8][9][10][11][12][13] Therefore, in the current condition in which a major

e focus on the development of China's vast hydropower resources has shifted to Tibet and other plateau regions. ese 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. erefore, 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. e 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. e research shows that the recommended temperature control and crack prevention measures can effectively reduce temperature stress.is study has a significant value as a reference for similar projects in highaltitude regions.

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According to similarity theory, with gypsum, cement, blanc fixe and water as similar material, a study on the relationship of physical and mechanic property and match ratio by orthogonal test. Effect disciplines of elastic modulus and ultimate compressive strength imposed by Content of various materials are worked out. Similar material of this experiment satisfies the requirements of selecting materials well, which therefore is suitable for model experiment.

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