Abstract:

The present research is to explore the seismic response features of the cutoff wall in dam foundation with deep overburden and to evaluate its seismic safety. Jinping rockfill dam was taken a case study. On the basis of 3-dimensional nonlinear static analysis, submodeling method was used to carry out time-history analysis on the foundation’s cutoff wall. The filling materials of dam and the alluvium deposit were simulated by Hardin-Drnevich dynamic constitutive model. The thin-layer contact element was used to simulate the contact relationship between the cutoff wall and the overburden. Results indicated that dynamic stresses showed a strong response in the upper part of the cutoff wall near the bank sides. After superposing the dynamic response with static response, the deformation and stress distribution rules changed slightly compared with those in the static state. Influenced by the terrain of deep and narrow valley and the turning point of the right bank, the vertical compressive stress extremum occurred in the turning point of the right bank of the mid-upper part of the wall instead of the mid-lower part as general rule shows. During the seismic history, the rupture area of the cutoff wall extended little, and the growth rate of vertical compressive stress extremum was only 3.5%. In conclusion, the influence of seismic load on the work condition of cutoff wall was not obvious.

Key words: rockfill dam , cutoff wall , deep overburden , dynamic analysis , submodeling analysis method