地裂缝环境下马蹄形地铁隧道与土体相互作用的研究

以穿越地裂缝带的西安地铁2号线为研究背景,通过数值模拟对地裂缝作用下马蹄形地铁隧道与土体相互作用的机理进行了研究。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,地裂缝处的隧道结构发生破坏。隧道的最大主应力位于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,宜采用分段式隧道结构。

Study on Interaction between Soil and U-shaped Metro Tunnel in the Environment of Ground Fissures

The Metro Line 2 in Xi＇an running across the ground fissures is taken as a research background, and the interaction between soil and U-shaped metro tunnel is studied by numerical simulation in the environment of ground fissures.The results show that the soil mass area is influenced by ground fissures and the vertical displacement gradually increases with the relative displacement increasing.When the hanging wall descends,the settlement deformation of footwall is maximum,and that of the hanging wall is minimum. The deformation area of tunnel lies on the two sides of presupposed ground fissure,and the area is enlarged with vertical relative displacement increasing.The tunnel structure damages at the ground fissures, when the relative displacement reaches 100 mm.The major principal stresses of tunnel are in the area of structure crack and shear failure.The major principal stresses of tunnel vary acutely.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 tunnel structure at the ground fissure.In the practical projects,the sectional type tunnel should be employed when the metro tunnel running across the ground fissures.