拱坝河谷三维地震动分析

The seismic field analysis of arch dam canyon

应用半无限相似单元模拟远场 ,通过动量守恒定理确定辐射阻尼 ,建立了有限元离散近场的三维波动计算模型 .采用中心差分法 ,可形成显式积分格式 ,整个近场域具有相同的精度与稳定性 .对于规则半无限域数值计算结果与理论值符合很好 ,说明本文模型是有效的 .最后 ,将此应用于半圆形及不规则拱坝河谷 ,计算结果表明地形影响显著 ,特别是薄弱山体地震动放大现象严重 .

A new semi\|infinite similar element is proposed to model the unbounded far field.The radiation damping is calculated according to the momentum conservation law.A procedure dealing with the soil\|structure interaction problem is presented on the basis of the finite element and viscous\|spring artificial bounds.The numerical results well agree with the analytical solution.The application of this new model to an example indicates that canyon seismic free field is obviously amplified by the irregular arch abutment.