下伏坎儿井暗渠对高速铁路路基稳定性影响

Influence of Underlying Qanat Tunnel on Stability of High-Speed Railway Subgrade

针对下伏坎儿井暗渠的高速铁路路基稳定性问题,采用有限元极限分析方法进行模拟研究。结果表明:路基荷载作用下下伏坎儿井暗渠路基的破坏模式主要有暗渠上部土体发生破坏和路基边坡发生滑动破坏2种,随着暗渠埋深和水平位置远离路基,破坏模式逐渐演变为路基边坡的自身破坏;暗渠临界深度分布曲线呈"W"形,且主要与暗渠位置、断面形状、断面尺寸有关,当暗渠位置位于临界深度分布曲线以下时,地基极限承载力不再随暗渠位置变化而改变,路基稳定性不再受暗渠影响;暗渠断面形状越圆滑,路基受力性能和稳定性越好,路基稳定时圆形暗渠的临界深度最小;暗渠断面宽度越大,路基稳定性越差,当圆形暗渠断面尺寸增大1倍时,暗渠临界深度增大约10倍。

The finite element limit analysis method was used to simulate the stability of high-speed railway subgrade underlying qanat tunnel.Results show that,the failure modes of subgrade underlying qanat tunnel under subgrade load mainly include the failure in the upper soil of the underground channel and the sliding failure of subgrade slope.With the buried depth and horizontal position of the qanat tunnel away from the subgrade,the failure mode evolves gradually into the self-failure of subgrade slope.The critical depth distribution curve of the underground channel is in the shape of“W”,which is mainly related to the location,shape and size of the qanat tunnel.When the location of the qanat tunnel is below the critical depth distribution curve,the ultimate bearing capacity of the foundation no longer changes with the location of the qanat tunnel,and the stability of the subgrade is no longer affected by the underground channel.The smoother the section shape of the channel is,the better the mechanical performance and stability of the subgrade are.The critical depth of the circular qanat tunnel is the smallest when the subgrade is stable.The larger the section width of qanat tunnel is,the worse is the stability of the subgrade.When the section size of the circular qanat tunnel is doubled,the critical depth of the qanat tunnel increases by about 10 times.