关键词: 隧道, 高地应力, 膨胀岩, 软岩大变形, 数值模拟, 变形控制

Abstract: To find a solution for large deformation of soft swelling rock with extremely high insitu stress in the Ningchan tunnel in Qinghai province, laboratory test in conducted on the physicomechanical properties of rock samples. The realtime monitoring results of the tunnel are compared with those of the Muzhailing tunnel, showing that the surrounding rock conditions of Ningchan tunnel is worse and the construction difficulty is much higher. Phenomena such as tunnel face collapse, large convergent deformation of surrounding rock, and cracking of supporting structure occurred. The maximum crown settlement reaches 451.2 mm and the maximum horizontal convergence reaches 549.6 mm. In the test construction section, the temporary invert was increased, the length of the anchor rod was increased, the support stiffness was increased, the advance support was strengthened, the rigidflexibility support was adopted, and reserved deformation was increased. The monitoring results show that the settlement and horizontal convergence of the crown are reduced by about 100 mm on average, and the horizontal control effect is 3%~4% more than that of the crown settlement, which is good in line with the numerical simulation results, indicating a good control effect of the recommended methods for Ningchan tunnel

Key words: tunnel, high insitu stress, swelling rock, large deformation of soft rock, numerical simulation, deformation control