Study On Effects Of High Concrete Gravity Dam Mechanical Properties Due To Cracking At Dam Hell

Study on mechanism of cracking at dam hell has been listed as key research issue during the past few years. Some beneficial exploration having been already carried out both in home and abroad, but the impact study of dam body with different dam hell crack location , depth and different water pressure distribution in fracture is not that much. The paper studied on the cracking of gravity dam hell by using finite element simulating software, and analyzed the static and dynamic characteristics of dam with different crack depth, water pressure in fracture and crack location, esp high dams. The main tasks of this paper are as following:First, the paper chose the case study and set up a view about 2D gravity dam models for numerical analysis, analyzed the laws on static and dynamic characteristics of dam with different crack depth, water pressure in fracture and crack location by using Elastic-viscoplastic Theory. The results show that the more the early crack close to the bottom of dam, the longer the depth of the crack, and the lower the natural vibration frequency will be. Thus, the effect on dam itself would be more obvious. Meanwhile, it also effective on static and dynamic characteristics of dam and it's stability while there is water pressure on the crack.Second, calculated the anti-slide safety coefficient of dam on various depth crack and location conditions by using the rigid limit equilibrium method and finite element method. The results demonstrated that when there crack, the crack tip and it's surrounding point safety factor would be lower in comparison with the no crack situation. And the overall safety factor will be reduced with the increase of crack depth. When the crack proceeded in a certain degree, the role of water pressure will seriously affect the safety of dam. Thus, the higher the position of the initial cracks, the poorer the anti-slide stability in this profile would be.Third, by applying theory of mixed-mode fracture criterion, this paper studied the crack stability in different depth, locations and water pressure in fracture. The research showed that the low initial location of cracks seriously affected its forward movement and made the worst stability on the base surfaces of gravity dam. Therefore, the dam's safety factor would be the most affected one. The stress intensity factor and hydraulic fracturing factor appeared notable effect of rectangular water pressure, then the effect of triangular water pressure distribution. In summary, cracks appeared relatively stable on condition that the extended crack is small. But when the crack extended to a certain degree, even if under triangle water pressure effect, cracks stability also deteriorated.