Study On Dynamic Characteristics Of High Earth-rockfill Dam Under Earthquake

As one of the most ancient dam type, earth-rockfill dam has many advantages of obtaining material locally, saving cost, strong applicability of landform and climate and so on,so it widely used in hydraulic and hydro-power engineering.With the development of water conservancy of expanding the size of earth rock dam,the dam is also more and more high, and rock and soil mechanics theory and computational analysis to improve the level of innovation and development and the construction method of large construction machinery, provides support for the construction of high earth rock dam, so many high earth and earth-rockfill dam dams are planning and construction. At present, the world’s highest dam has reached 335 m, the earth-rockfill dam under construction and proposed in China also has a lot of dam more than 200 m,even more than 300 m. If the safety of these high earth earth-rockfill dam dam which is not absolute security, the consequences would be unthinkable, but most of these high dams were built in the western area of strong earthquakes, the seismic performance will become the dominant factors of dam safety, So it is necessary to study the seismic dynamic characteristics of high earth rock dam specially and systematically.In this paper, the dynamic characteristics of high earth-rockfill dam on the earthquake were analyzed. The shear wedge method is used and combined with the response spectrum method and the mode superposition method, considering the characteristics of earth rock dam material nonlinear static and dynamic, focused on researching high earth-rockfill dam of the maximum acceleration, the maximum shear strain, the maximum shear stress distribution in earthquake, analysis the rules and values of seismic dynamic distribution coefficient. Using the finite element software ABAQUS, introduced Duncan-Chang E~? model as static constitutive model and equivalent linear model as dynamic constitutive model is embedded in ABAQUS user subroutine, respectively finished researching The simulation of construction process of dam construction, dam of the static analysis and the dynamic responses of the dam under earthquake of the Pubugou earth-rockfill dam.The results show that:1) with the increase of seismic design intensity, the seismic dynamic coefficient on top of the dam are reduced, for the same earth-rockfill dam under the same seismic design intensity, the seismic dynamic coefficient on top of the dam decreased with the increase of earthquake acceleration. It shows that the dynamic seismic coefficient is not only related with the seismic design intensity, but also has great relevance with dam height.2) For high earth-rockfill dam, the dam body acceleration peak value appears larger amplification effect, high above 0.9 times in the dam area appears approximate linear growth,and other internal parts acceleration distribution more uniform relatively. the time of themaximum acceleration there is no directly contact with the peak time of seismic wave, only related with seismic wave itself waveform and the material properties of earth-rockfill dam.3) To put forward a proposal to dynamic coefficient distribution proposal map and the recommended value of dynamic coefficient.With the dam height is increasing continuously, the average shear strain overall the dam and the damping ratio is also increased,improving the soil on the seismic energy consumption, which to some extent explain the maximum acceleration decreases with the height increasing.4) Whether in the completion stage, storage period, or in the process of the earthquake, near the 2/3 dam height will be the arch effect is the most serious and the hydraulic fracturing of the possibility of the largest area, it is the largest possibility region of the core wall cracks, core wall permeability is the weakest link, so in the design, construction and monitoring of the process should focus on.