降雨条件下膨胀性黄土隧道支护结构破坏特征

Analysis of Failure Feature of Expansive Loess Tunnel Support Structure Under Rainfall Condition

为了揭示膨胀性黄土隧道在降雨作用下围岩与支护破坏机理,采用有限元软件对膨胀性黄土地层中的静游隧道开挖进行数值模拟。结果显示:由于降雨,隧道拱顶上方塑性区贯通并产生较大位移,隧道上部坡体产生大面积塑性区并发生滑移;隧道支护结构破坏位置与实际情况一致,且由于膨胀力的作用隧道偏压更明显,应力大的一侧支护结构破坏更显著。因此需要对围岩进行加固,尤其是在应力较大的一侧应加强初期支护的强度。

In order to study surrounding rock and support failure mechanism of expansive loess tunnel under rainfall condition,numerical simulation of Jingyou tunnel excavation in the expansive loess stratum was made by using the finite element software. The results show that plastic zone is interconnected and a larger displacement is generated above the tunnel vault and a large area of plastic zone is produced and the slippage occurs in the upper slope of tunnel due to the rainfall,the failure position of the tunnel support structure is consistent with the actual situation,tunnel bias is more obvious under the action of expansive force,and the damage of support structure is more significant on the side of large stress,which means that the surrounding rock should be reinforced and the initial support strength should be increased on the side of large stress.