青藏高速公路路基地震动力响应分析
Seismic dynamic response analysis of embankment along the Qinghai-Tibet Expressway

为了研究即将修筑的青藏高速公路在地震荷载作用下的动力响应特征,拟合出该区50 a超越概率为63.5%,10.0%和2.0%的人工地震波。在数值模拟的基础上,运用二维非线性动力有限元分析方法,建立整体式和分离式2种典型的高速公路路基横断面结构,对比分析不同超越概率地震荷载作用下2种形式路基的动力响应特征。研究结果表明:分离式路基在路基表面中心和天然地表中心2处的加速度放大系数均小于整体式路基,而其路基表面的水平、垂直峰值位移均大于整体式路基;2种路基左右两侧坡脚下方土体内剪应力集中分布;随着输入地震波峰值加速度的增大,2种路基表面的水平峰值位移均呈线性增长趋势,垂直峰值位移呈指数函数增长趋势。分析结果可为多年冻土区高等级公路抗震设计提供相应参考。
The artificial earthquake waves with the exceeding probability for 63.5%, 10% and 2% in 50 years related to this areas were established to study the dynamic response characteristics of proposed Qinghai-Tibet Expressway under seismic loading. Based on numerical simulation, and the two-dimensional nonlinear dynamic finite element method, cross sections of integral and separated embankment were respectively established for the analysis of the dynamic response characteristics under different exceeding probability of seismic wave. The results of this study are summarized as follows. Acceleration amplification coefficients of separated type embankment at the center of both embankment surface and natural ground surface are less than that of integral type embankment. However, horizontal displacement and vertical displacement of separated type embankment are greater than that of integral type embankment. Meanwhile, the shear stress of both integral and separated embankment around two sides are concentrated under the slope feet. With the increase of peak acceleration of seismic waves, horizontal peak displacement on the surface of the embankment increases as the law of linear trend, and the vertical peak displacement increases as the law of exponentially function. These results could provide references and bases for seismic design of expressway in permafrost regions