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以西安地铁明挖区间隧道穿过地裂缝带为研究背景,通过几何比1∶5的大比例尺地裂缝与地铁隧道模型试验,研究了地裂缝活动引起地铁隧道地层应力与位移变化规律。试验结果表明:地裂缝活动在上盘地层中产生负的附加应力,出现应力降低区,而在下盘产生正的附加应力,出现应力增强区,且距离地裂缝越远附加应力越小。随上盘沉降量的增大,上盘隧道顶部地层应力增加,两侧逐渐减小,而下盘隧道顶部地层应力逐渐减小接近于零,两侧地层应力则逐渐增大。地层位移和地表沉降变形随地裂缝位错量增加而增大,横向呈现上、下盘相反的变化规律,同时上盘地表出现与地裂缝近似垂直的纵向拉张裂缝,影响范围约为2倍隧道宽度,下盘地表出现与地裂缝大致平行的横向拉张裂缝,影响宽度约为2.5倍隧道宽度。研究结果可为地裂缝环境下地铁隧道沿线城市规划与地裂缝灾害防治提供参考。
Taking the ground clearance tunnel in the open cut section of Xi’an Metro as the research background, through the model test of large scale ground fissures and subway tunnels with geometric ratio of 1: 5, the variation rules of the stress and displacement of underground tunnels caused by ground fissures are studied. The results show that the ground fissure activity produces negative additional stress in the upper strata, with stress reduction zone, and positive additional stress in the lower plate, resulting in stress-enhanced zone, and the additional stress is farther away from the ground fissure. As the settlement of the upper plate increases, the stress of the top layer of the upper plate tunnel increases and both sides decrease gradually. However, the stress of the top layer of the lower plate tunnel decreases gradually to zero and the stress on both sides gradually increases. The formation displacement and the surface subsidence deformation increase with the increase of the dislocation amount of the ground fissure, and show the variation law of the upper and lower plates in the horizontal direction. At the same time, the vertical tension cracks perpendicular to the ground fissure appear on the upper plate, affecting about 2 times tunnels Width, appear on the surface of the lower plate and ground fissures are generally parallel to the transverse tension cracks, affecting the width of about 2.5 times the tunnel width. The results can provide references for the urban planning and the prevention and control of ground fissure disasters along the subway tunnel under ground fissures.