进洞高程对黄土隧道洞口衬砌和仰坡动力响应的影响

Influence of portal elevation on lining and slope dynamic response of loess tunnel portal section

针对黄土边坡与隧道洞口段衬砌的相互作用问题,运用数值模拟的方法分析了以不同进洞高程进洞时黄土隧道洞口段衬砌的动力响应特征和洞口仰坡的动力稳定性。结果表明:进洞高程越大,洞口段隧道衬砌的位移响应与内力响应越大;随着进洞高程的增大,坡面位移放大系数在减小,不同进洞高程进洞时坡面位移放大系数均呈先增大后减小再增大的变化趋势。在0.2~0.6H时变化最为剧烈,0.4H左右时位移放大系数达到了最大值;不同进洞高程进洞时坡面中心和水平方向距离隧道结构1.5D处的坡面位移放大系数变化趋势基本一致,其大小关系为:纯边坡位移放大系数<有隧道结构中面位移放大系数<距隧道1.5D位移放大系数;随着进洞高程的增大,剪应变增量和坡面位移均在减小,坡面的稳定性在增强。该研究可为黄土地区隧道进洞高程的选择提供一定的参考。

In view of the interaction between loess slope and tunnel portal lining,the dynamic response characteristics of loess tunnel portal and the dynamic stability of entrance slope at different tunneling altitude on slopes are analyzed by numerical simulation method.The results show that:the higher of the tunneling altitude on slope,the greater of displacement response and internal force response of the tunnel structure;the magnification coefficient of the slope displacement gradually decreases with the increase of the tunneling altitude on slope;the amplification coefficient of the slope displacement are increases first,then decreases,finally increases again at different tunneling altitude on slopes,and the change is most serious at 0.2H^0.6H and reaches the maximum value about 0.4H;there are the same variation trend of the amplification coefficient at the center of the slope and at the distance of 1.5D from the tunnel in the horizontal direction.For the amplification coefficient,it shows that the slope without tunnel is the smallest,the center of the slope is the medium,and distance from the tunnel of 1.5D in the horizontal direction is the largest.The shear strain increment and slope displacement decrease with the increase of tunneling altitude on slope,meanwhile the slope stability is strengthening.The research results can provide some references to the selection of tunneling altitude on slope in loess area.