Finite Element Analysis of Dynamic Response of Maoergai Earth-rockfill dam in Earthquake Disaster

The dynamic responses of Maoergai earth-rockfill dam are calculated by nonlinear finite element method (FEM) under the action of three different seismic waves, the horizontal peak ground accelerations (PGA) which are 200 gal (exceedence probability of 5% in 50 years), 258.06gal (exceedence probability of 5% in 100 years) and 336.81gal (exceedence probability of 2% in 100 years), respectively. In static calculation, the nonlinear elastic Duncan-Chang constitutive model has been adopted to simulate soil behavior. In dynamic calculation, the soil is considered to be viscoelastic material and the equivalent linearization dynamic constitutive model is applied for simulation. The permanent deformation is calculated by Shen Zhujiang residual strain potential model. The results indicate that the acceleration presents whiplash effect characteristic on top of the dam. Since the stress-strain relationship of rockfill material is nonlinear, the acceleration amplification decreases as the increase of input acceleration peak values. The dynamic displacement is increased as the height of node increases. Due to the restriction effect of "V" shape valley, the dynamic response decreases gradually from the center of valley to two banks. The increment of maximum dynamic shear stress is not obvious as the increase of input peak values because of the nonlinear characteristic of rockfill material. The maximum dynamic principal compressive and tensile stresses in both cutoff wall and covered way are less than the allowable strength. The permanent deformation increases gradually as the increase of input acceleration peak value. When the input peak values of seismic waves are 200 gal, 258.06 gal and 336.81 gal, the maximum vertical permanent deformations are 56 cm, 70.3 cm and 85.9 cm, respectively.