A three-dimensional numerical model was established to simulate the excavation of two-lane tunnels with different longitudinal spacing in the same direction.Following the principle of early warning and influence degree of control values,the deformation and stress of the cavern,the plastic zone and the stress and strain of the initial support structure were analyzed.Calculate the influence of different vertical spacing on the excava-tion of the left and right lines.The results show that the double-line tunnel has a certain lateral spacing,and the vertical spacing increases the stability of the surrounding rock.When the V-type surrounding rock step construction method is used to maintain the longitudinal spacing of the tunnel between two subways 1.5 times the diameter and above,the stress-strain extremum is smaller than the control value.The 85%and the degree of impact is less than 10%,and the surrounding rock and supporting structure are relatively stable,which is a reasonable longitudinal distance.%建立三维数值模型模拟不同纵向间距双线隧道同向开挖,遵循控制值预警和影响程度原则,分析其洞周收敛变形及应力、塑性区域、初期支护结构的应力及应变变化规律,计算不同纵向间距左右线开挖影响程度.结果表明:双线隧道横向间距一定,纵向间距增大围岩稳定性增强,V类围岩台阶法施工双线地铁区间隧道纵向间距保持1.5倍洞径及以上时,应力应变极值小于控制值的85%且影响程度小于10%,围岩及支护结构相对稳定,为合理纵向间距.
展开▼
