高地应力状态下软岩公路隧道的大变形机理与规律研究

高地应力区软岩隧道地质条件复杂,使软岩隧道变形控制难度加大。以某一工程实例为对象,运用MIDAS/GTS软件建立了软岩公路隧道模型,分析了不同侧压力系数下对高地应力软岩隧道开挖变形的影响作用。研究结果表明:随着侧压力系数的增大,隧道围岩水平位移由向隧道外挤压变形转化为向隧道内收敛变形,K值在0.5~0.75时,存在一个水平位移零点,最终水平变形量为0;对于隧道竖向位移变形,当侧压力系数小于1时,隧道最大竖向位移出现在拱顶处。当侧压力系数大于1时,上拱变形加强,但整体依然表现沉降变形,隧道最大竖向位移出现由拱腰转移到拱间处。K值在1附近时,隧道水平变形和拱顶变形所形成的最终变形量相等,可根据现场对水平位移和拱顶位移间的位移关系来判定隧道围岩侧压系数的大致取值范围。

Study on Large Deformation Mechanism and Law of Soft Rock Highway Tunnel Under High Ground Stress

The soft rock tunnel with high ground stress area is difficult to control the deformation control of the soft rock tunnel due to the complicated geological conditions.In this paper,a soft rock highway tunnel model is established by using MIDAS/GTS software,and the effect of different pressure coefficients on the deformation of the high-stress soft rock tunnel is analyzed by using MIDAS/GTS software as the object.The results show that,with the increase of the lateral pressure coefficient,the horizontal displacement of the surrounding rock of the tunnel is converted into the convergent deformation in the tunnel from the outward extrusion deformation to the tunnel,and when the K value is between 0.5 and 0.75,there is a horizontal displacement zero and the final horizontal deformation is 0;for the deformation of the vertical displacement of the tunnel,When the lateral pressure coefficient is less than 1,the maximum vertical position of the tunnel moves out of the present vault.When the lateral pressure coefficient is greater than 1,the upper arch deformation is strengthened,but the whole still shows the settlement deformation,and the maximum vertical displacement of the tunnel appears from the arch waist to the arch space.When the K value is near 1,the final deformation of the tunnel is equal to that of the vault,and the approximate value range of the lateral pressure coefficient of the tunnel surrounding rock can be determined according to the displacement relation between the horizontal displacement and the vault displacement in the field.