黄土隧道洞口段饱和滑坡体处理

Treatment Measures of Saturated Landslide at the Portal Section of Loess Tunnel

某新建铁路刘坪隧道出口段穿越不稳定富水饱和黄土地层,洞口段为疑似滑坡体。为保证工程施工及运营安全,采用现场钻孔补勘和水文地质调查等方法,确定了滑坡体的规模、滑动方向,结合区域地质构造,分析了洞口段滑坡体的成因,并结合施工过程,提出了洞外设置防护桩及坡脚反压回填、洞内超前帷幕注浆与基底加固等相结合的处理方案。目前,该隧道已贯通。实践证明:(1)防护桩及坡脚反压回填对控制滑坡体位移效果明显;(2)帷幕注浆能有效提高土体稳定性;(3)帷幕注浆能有效减少洞内涌水,并可降低土体含水率约10%。

The Liuping tunnel portal section of a new railway crosses unstable water-rich saturated loess stratum,which is suspected landslide body.In order to ensure the safety during construction and operation,a method of on-site drilling and hydrogeological survey was used to determine the scale and sliding direction of the landslide body,and analyzed the cause of the landslide body combined with the regional geological structure.According to the construction process,a treatment that combining the measures of setting anti-slide pile outside the tunnel,back pressure backfilling at slope foot,advanced curtain grouting inside the tunnel and foundation reinforcement was proposed.At present,the tunnel has been penetrated,and the application has showed that:(1)the anti-slide pile and back pressure backfilling are obviously effective in controlling the displacement of landslide body;(2)the curtain grouting can effectively improve the stability of saturated loess;(3)the curtain grouting can effectively reduce the water inflow in the tunnel,and reduce the soil moisture content by about 10%.