Influence of Different Excavation Methods on Stress Characteristics of Shallow Buried Loess Bifurcation Tunnel
In order to optimize the construction method of shallow buried loess bifurcation tunnel,the stress and deformation characteristics of bifurcation are analyzed by using the middle pilot tunnel method and the three pilot tunnel method based on Baishi No.2 Tunnel.The results show that:(1)due to the influence of construction process transformation,the vault settlement at the bifurcation and the horizontal displacement of the arch foot have complex trends.After excavation,the vault settlement of the left and right holes of the middle pilot tunnel method is-28.62 mm and-29.95 mm,respectively,and the three pilot tunnel method is-27.93 mm and-28.94 mm,respectively,the values are not much different,but the latter method has less impact on long-span section.The horizontal displacement of the arch foot of the left and right holes is 13.69 mm and-14.28 mm respectively by the middle pilot hole method,and10.78 mm and-12.13 mm respectively by the three pilot hole method.The construction of the three pilot hole method is beneficial to control the surrounding convergence of the tunnel.(2)Compared with the three pilot tunnel method,the stress difference between the surrounding rock of the left and right vaults of the middle pilot tunnel method is larger,and the construction bias problem is more obvious.(3)Both methods can meet the construction requirements,but the three pilot tunnel method is more conducive to controlling the convergence around the tunnel,and has little effect on the large-span section.
NETL
NSTL
万方数据
维普
