深埋碳质板岩隧道采用不同开挖方法时围岩及初期支护变形特征

大理至瑞丽铁路高黎贡山隧道为深埋碳质板岩隧道,利用MIDAS/GTS建立数值模型研究该隧道开挖过程中围岩及初期支护变形特征。结果表明:含仰拱全断面开挖在控制围岩变形和剪切破坏方面比不含仰拱全断面开挖更有优势,掌子面渗水导致实测的围岩变形量稍大于数值模拟结果;围岩压力和钢拱架应力出现急剧增长、增速变缓、趋于稳定3个阶段。急剧增长阶段围岩压力和钢拱架应力的最大值分别占整体最大值的70%～85%和60%～85%,围岩变形、围岩压力和钢拱架应力的最大值均出现在拱顶,较大值均出现在右拱腰和左拱脚,存在右上左下的偏压现象。

Deformation Features of Surrounding Rock and Primary Support for Tunnel in Deep Buried Carbonaceous Slate with Different Excavation Methods

Gaoligongshan tunnel of Dali-Ruili railway is a deep buried carbonaceous slate tunnel,a numerical model to study the deformation characteristics of surrounding rock and primary support in tunnel excavation was established by using MIDAS/GTS.The results show that full section excavation including inverted arch is more advantageous than excavation not including inverted arch in controlling deformation and shear failure of surrounding rock,the measured surrounding rock deformation caused by water seepage on the tunnel face is slightly larger than that of numerical simulation,surrounding rock pressure and steel arch stress show such three stages as sharp increasing,the growth rate slowing down and tending to be stable.The maximum values of surrounding rock pressure and steel arch stress are 70%~85%and 60%~85%of global maximum respectively in the stage of sharp increasing,the maximum values of surrounding rock deformation,surrounding rock pressure and steel arch stress appear at the vault,the larger values appear in the right arch waist and left arch foot,and there is phenomenon of upper right lower left bias.