分幅距离对青藏高速公路分离式路基动力响应的影响

为研究地震波作用下分离式路基的动力响应特性,结合现场钻孔资料,以标准断面的分离式路基为研究对象,采用二维非线性动力有限元非关联流动法,建立2幅坡脚距离分别为5,10,15和20 m的路基模型。通过施加50 a超越概率2%,10%和63%的地震波,得到分幅距离变化对路基地震动力响应的影响效应。研究结果表明:路基表面的Mises应力值大小受坡脚距离变化影响较大,对天然地表与坡脚影响微小,而对剪应力S12值大小的影响规律与此相反;随着坡脚距离的增加,路基表面与天然地表的水平峰值位移呈现先升高后降低的变化规律,在10 m坡脚距离的参考点水平峰值位移出现极大值。研究结果为青藏工程走廊内的路基选型布线与抗震设计提供一定参考。

Influence of distance between two lines on seismic dynamic response of separated embankment along the Qinghai-Tibet Expressway

In order to study the dynamic response characteristics of separated embankment under seismic wave, combining with field borehole data, taking separated embankment with standard section as the research object, the two-dimensional non-linear dynamic finite element non-correlative flow method was used to establish the separated embankment model with the spacing of 5, 10, 15 and 20 m respectively between left and right slope toe. The effect of change of distance between two lines on the seismic dynamic response of embankment was obtained by applying seismic waves with the exceeding probability of 2%, 10% and 63% in 50 years. The results show that the Mises stress value of embankment surface is greatly affected by the change of slope toe distance, and that the influence on natural surface and slope toe is small. While these effect laws are exactly opposite to shear stress S12 value. With the increase of slope toe distance, horizontal peak displacements of separated embankment surface and natural surface show the law of first increasing and then decreasing, meanwhile peak displacement of reference point reach maximum value when slope toe distance is equal to 10 m. This study result is expected to provide reference for type selection and a seismic design of separated embankment in QTEC.