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根据西安地裂缝的分布特征与活动方式,结合西安地铁二号线的实际情况,建立地质模型。通过数值计算,分析了地裂缝环境下隧道的变形和受力,并据此来研究穿越地裂缝隧道的设防范围、重点设防位置;研究了地裂缝环境下围岩压力的分布特征,为隧道受力模型的简化提供依据。由分析结果可见,地裂缝环境下隧道变形和受力的主要设防范围为上盘距离地裂缝40 m至下盘距离裂缝30 m共70 m范围;隧道纵向受力的最危险位置为裂缝两侧15～20 m处,隧道受剪最危险范围为裂缝两侧各15 m之内;在上盘地裂缝影响范围内隧道顶部的竖向围岩压力远远大于底部竖向围岩压力,此时可以忽略隧道底部土体的竖向作用力,将结构当作一根以沉降变形区两端为支撑的简支梁构件,采用极限平衡理论求解作用于隧道顶部的竖向围岩压力,并据此进行纵向抗弯设计。
According to the distribution and activity of ground fissures in Xi’an and the actual conditions of Xi’an Metro Line 2, a geological model was established. Through numerical calculation, the deformation and stress of the tunnel under ground fissure are analyzed, and the fortification range and key fortification position of the tunnel crossing the ground fissure are studied accordingly. The distribution characteristics of surrounding rock pressure under the ground fissure are studied. Simplify the force model to provide the basis. From the analysis results, it can be seen that the main fortification range of tunnel deformation and stress in ground fissure environment is 40 m from the ground fissure from the upper plate to 30 m within 30 m of the lower plate fissure 30 m; the most dangerous position of the tunnel longitudinal stress is the two sides of the fissure At the depth of 15-20 m, the most dangerous range of tunnel shearing is within 15 m on both sides of the fracture. The pressure of vertical surrounding rock at the top of the tunnel is far greater than the pressure of vertical surrounding rock at the bottom of the tunnel due to the influence of ground fissures The vertical force of the soil at the bottom of the tunnel can be neglected. The structure is regarded as a simple supported beam supported by the two ends of the settlement deformation zone. The limit equilibrium theory is used to solve the pressure of vertical surrounding rock acting on the top of the tunnel. According to This longitudinal bending design.