Abstract
Hydraulic fracturing is one of the most important factors affecting the safety of earth and rockfill dam. In this paper, the extended finite element method (XFEM) is used to simulate the hydraulic fracturing behavior in an actual high earth and rockfill dam. The possibility of hydraulic fracturing occurrence is analyzed, and the critical crack length is obtained when hydraulic fracturing occurs. Then, the crack propagation path and length is obtained by inserting initial crack of different lengths at different elevation. The results indicate that hydraulic fracturing will not occur without the permeable weak surface (initial crack). The critical initial crack length required for hydraulic fracturing is 5.3 m of the calculation model in this paper. The propagation length decreases with the increase of elevation, and the average propagation length decreases from 9.4 m to 3.4 m. Furthermore, it is proved that the direction of crack propagation has a certain angle with the horizontal plane toward the downstream. Considering the up-narrow and down-wide type of the core wall, the possibility of hydraulic fracturing to penetrate the core is extremely high when the upper part of the core wall reaches the critical crack length.
Highlights
In recent years, with the needs of hydropower construction, hydropower energy development is increasing rapidly in China. erefore, many high earth and rockfill dams have been designed or under construction, such as the Changhe (240 m in height) in Sichuan province, Shiziping (136 m in height) in Hebei province, and Nuozhadu (261.5 m in height) in Yunnan province
If the calculated critical water pressure is less than the water pressure at the crack tip, the new crack is determined to appear. e propagation of the initial crack is determined by whether the accumulated energy of the crack propagation is more than the fracture energy of the core material. us, the critical crack length under the full reservoir water level can be obtained by establishing the relationship between the initial crack length and the reservoir water level when the hydraulic fracturing occurs
If the water level is greater than the reservoir water level, the water pressure on the surface of the core wall is the maximum reservoir water level while the water level on the crack surface is applied according to the actual water level. e main purpose of this method is to research the critical length of initial crack under full water level
Summary
With the needs of hydropower construction, hydropower energy development is increasing rapidly in China. erefore, many high earth and rockfill dams have been designed or under construction, such as the Changhe (240 m in height) in Sichuan province, Shiziping (136 m in height) in Hebei province, and Nuozhadu (261.5 m in height) in Yunnan province. Li et al [6] used the smeared cracking theory to simulate the process of hydraulic fracturing in a certain earth and rock ll dams. By using the XFEM, the crack is allowed to pass through the element; cracks with complex shapes can be calculated in regular mesh without remeshing Because of these advantages, the XFEM has been considered as a more accurate and e cient method in many areas, such as dynamic crack propagation, shear zone evolution, and multiphase ow. No researchers have used the XFEM to simulate crack problem in earth and rock ll dam engineering. It is possible to simulate hydraulic fracturing in earth and rock ll dam by using the XFEM. The XFEM is used to simulate the hydraulic fracturing in an actual high earth and rock ll dam. Related research achievements are of great signi cance for the prevention and control of hydraulic fracturing in actual earth and rock ll dam construction
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