【摘要】 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。更多还原

【Abstract】 Based on the distribution and movement of ground fissures and the condition of No.2 metro tunnel in Xi’an,a geological model is established.Through the numerical analysis of finite element model,the protection range of the metro tunnel crossing ground fissures and its most dangerous section are confirmed by analyzing its deformation and stress states,and then,the distribution characteristics of surrounding rock pressure are studied so as to provide a basis for simplification of the model to calculate the stress of the metro tunnel crossing ground fissure.The results show that the main protection range of deformation and stress of the metro tunnel is from the location at the upper wall 40 m to that at the lower wall 30 m away from the fissure,that the most dangerous section is mainly distributed at the place of the ground fissure with a distance of 15~20 m at both sides,and that the structure in the range of 15 m away from the fissure at both sides suffers the maximum shear stress.The vertical pressure above the metro tunnel at the upper wall near the fissure is greater than that at the bottom,and the latter may be ignored.Therefore,the section of the metro tunnel crossing the fissure should be regarded as a beam which is sustained at the two sides of the subsiding area,and the vertical pressure of wall rock used to confirm the flexural torque produced by the activity of ground fissures should be calculated by the theory of stress transfer.更多还原