基于改进的地震动态分布系数及修正D-P模型的高土石坝坝坡抗震稳定分析

Seismic Stability Analysis of High Earth-Rock Dams Based on Improved Dynamic Distribution Coefficients and a Modified Drucker-Prager Model

采用有限元法研究高土石坝的地震加速度分布,提出高度为250m级的土石坝建议地震加速度动态分布系数图示。在此基础上,基于修正的Drucker-Prager弹塑性模型,利用强度折减法对高度为250m级的土石坝坝坡抗震稳定性作进一步分析,结果表明随着坝体地震加速度动态分布系数的降低,坝坡的临界安全系数有所提高。

The seismic acceleration dynamic distribution coefficient suggested in the current code for seismic design of hydraulic structure（DL5073-1997）is suitable for earth-rock dams that are below a height of 150 m.However,currently,most earth-rock dams being designed are higher than 150 m.Compared with low-height dams,tall dams have less constraint from the stiffness of their foundation and the self-vibrating period of the high dam is prolonged under cyclic loading.During the seismic response of the dam body,the high order self-vibrating period has more opportunities to coincide with the seismic predominant period and high order vibrations are easily activated and amplified,which causes the seismic acceleration distribution to be dissimilar to that in short dams.Using the finite element method,the seismic acceleration distribution of high earth-rock dams can be analyzed.The analytical results allow for the determination of the seismic acceleration dynamic distribution coefficient of earth-rock dams 250 mlevel in height.On the basis of these results,employing a modified Drucker-Prager model and strength reduction technique,further research on the slope seismic stability analysis of earth-rock dams 250 mlevel in height was made.The conclusion of this analysis was that a decrease of the seismic acceleration dynamic distribution coefficient in the dam body causes an increase in the critical value of safety factor of the dam slope.