隧道交叠段变形规律及支护应力研究

新建隧道下穿既有隧道时,交替开挖工序可能会对既有隧道产生不利影响,文中以某公路隧道交叠段为对象,对新建隧道开挖进行全过程数值模拟,分析开挖过程对既有隧道底板变形的影响,同时考虑交叠段隧道结构之间相互作用关系,分析新建隧道支护应力及围岩变形。结果表明,新建隧道开挖后,竖向位移最大值出现两主洞隧道拱顶部位,水平位移最大值出现主洞左、右边墙部位,主洞左、右边墙角部位可能出现局部拉裂破坏,既有隧道底板沉降最大值出现在新建隧道主洞顶部上方。

Deformation and Construction Stress Study of Tunnels Overlapping Section

When the new tunnel underpass the existing tunnel,the alternating excavation process may have adverse effectson the existing tunnel.Taking the overlapping section of a highway tunnel as an object,the whole excavation process of new tunnel is numerically simulated,and the influence of excavation process on the deformation of existing tunnel floor is analyzed.Considering the interaction between adjacent tunnel structures,the supporting stress and surrounding rock deformation of new tunnel are analyzed.The results show that the maximum vertical displacement appears in the vault and the maximum horizontal displacement appears in the left or right side wall.There may be tensile damage in the corner of left and right side,and the maximum settlement of the old tunnel floor appears above the top of the new tunnel.