不同强度地震作用下的心墙堆石坝三维动力液化分析

东圳水库大坝位于福建省莆田市城厢区,该水利枢纽处于华南沿海地震带北段,由于水库建设时我国尚未有抗震设防烈度标准,因此亟需对其抗震稳定性进行复核。以东圳水库大坝为原型,结合已有的地震资料,选用Byrne液化模型,采用FLAC3D软件,研究了在50年超越概率10%、5%和2%地震作用下坝体填料的液化特征及最终位移情况。结果显示,在地震作用下,坝体上游砂砾石填料会发生局部液化,且液化区随着地震强度的增大而增加,但尚未出现大面积连续液化区;坝体填料发生液化后,产生了有限度的塑性变形,其变形量也随着地震强度的增大而有所增加;除坝顶较小区域外,坝体总位移量相对较小,对大坝整体稳定性不会产生显著影响。研究结论可以为大坝的抗震加固和治理措施的选择提供依据和参考。

Three-dimensional Liquefaction Analysis of Core-wall Rockfill Dam under Different Intensity Earthquakes

Dongzhen dam,located in Putian City of Fujian Province,is just in the northern part of South China coastal seismic zone.This dam was built in 1950swhen the seismic fortification intensity standard hasn′t been set in China.The seismic performance of the dam should be assessed according to current standards.Choosing Dongzhen dam as a proto-type and adopting Byrne dynamic pore pressure model,the liquefaction and displacement characteristics of this dam was studied by the finite difference software FLAC3D.Three seismic acceleration time history curves with exceeding probability of 10%、5%and 2%in 50years were selected as input load in order to meet the needs of the anti-seismic design.Results show that the gravel filling in the upstream part liquefies in some domain under seismic load,and the liquefied area increases with the earthquake intensity.But the volume of liquefied area is still relatively small compared to the non-liquefied area.The liquefaction of the gravel filling results in permanent deformation in dam body. The deformation also increases with earthquake intensity.However,the displacement is relatively unimportant except the dam crest.The liquefaction displacement has no fatal impact on the stability of the main dam.This study can throw light on the seismic resistance design and reinforcement of the dam.