浅埋黄土隧道土石分界高度对初期支护结构安全性的影响分析

为获得浅埋黄土隧道土石分界高度对初期支护结构安全性的影响,文章以临县隧道为工程背景,采用数值模拟的方法研究了浅埋土石分界高度及土石分界面位置对隧道初期支护结构安全性的影响。结果表明:土石分界致使隧道初期支护结构安全系数发生突变,分界面倾斜时安全系数分布不对称。同一种埋深条件下,随着土石分界面位置的下移,土石分界面以上部分偏压减弱,分界面以下的部分偏压增强。同一界面深度条件下,隧道初期支护结构左右断面偏压情况随着埋深增加而增大。当土石分界面分别位于隧道上导坑和中下导坑、分界面倾角为10°时,可通过增加20%隧道左侧荷载或减小20%右侧抗力系数来进行荷载计算。

Influence of Earth-Rock Interface Height on Safety of Primary Support Structure of the Shallow-buried Loess Tunnel

In order to understand the influence of earth-rock interface height of the shallow-buried loess tunnel on safety of primary support structure,the effect of earth-rock interface height and position on safety of primary support is studied by numerical simulation based on the Linxian tunnel.The results show that:the earth-rock interface results in sudden change of safety factor of the primary support structure and the distribution of safety factor is asymmetric when the interface is inclined.Under the same buried depth,the asymmetric pressure above the earth-rock interface decreases while the asymmetric pressure below the earth-rock interface increases with downward movement of the earth-rock interface.Under the same interface depth,the asymmetric pressures of the left and right sections of the pri mary support increase with the increase of the buried depth.When the earth-rock interface is located in upper heading,middle heading and lower heading,and the interface inclination is 10°,the load can be calculated by increasing the load by 20%on the left side of tunnel or reducing resistance coefficient by 20%on the right side of tunnel.