地面不均匀沉降对马蹄形隧道作用的研究

Study on Interaction between Soil and U- shaped Metro Tunnel in Ground Differential Settlement

以西安地铁2号线穿越地裂缝带为研究背景，通过数值模拟对地面不均匀沉降作用下马蹄形地铁隧道与土体的相互作用机理进行了研究。研究结果表明，随着上下盘位错量的增加，地裂缝处受影响的土体范围逐渐增大，土体的竖向位移也逐渐变大；上盘下降过程中，下盘隧道顶部沉降变形最大，上盘隧道顶部沉降变形最小；隧道的变形区域出现在预设地裂缝两侧，并且随着竖向位错的增大而增大。当错距d=100mm时，地裂缝处隧道结构发生破坏。隧道的最大主应力位置出现在结构出现裂缝和受剪切破坏的区域，随着位错量的增加，隧道的最大主应力变化剧烈。地裂缝处隧道结构上部靠下盘区域受拉，靠上盘区域受压，隧道结构下部靠下盘区域受压，靠上盘区域受拉。在实际工程中，地铁隧道穿越地裂缝时，宜采用合理分段式隧道结构。

Taking the Metro Line 2 in Xi^m passing through the ground fissures as research background, the interaction mechanism between soil and U -shaped metro tunnel is studied by numerical simulation in ground fis- sures. The results show that the soil mass area influences by ground fissures and the vertical displacement gradually increases with the relative displacement increasing. While the hanging wall descending, the settlement deformation of footwall is maximum, and that of the hanging wall is minimum. The deformation area of tunnel lies in the two sides of presupposed ground fissure enlarging with vertical relative displacement increase. The tunnel structure would be damaged at the ground fissures when the relative displacement reaches to 100mm. The major principal stress of tunnel is in the area of structure crack and shear failure, which varies sharply with the displacement in- crease. The footwall part is in tension and the hanging wall part is under pressure on the top of tunnel structure at the ground fissure. The footwall part is under pressure and the hanging wall part is in tension on the bottom of tun- nel structure at the ground fissure. During practical construction, the sectional tunnel should be adopted when the metro tunnel passing through the ground fissures.