LIU Xue-zeng, CAI Guang-yuan, YANG Fan, SANG Yun-long, WU Jian-xun
China Journal of Highway and Transport. 2017, 30(8): 57-65.
In order to determine the deformation controlling indicators for staggered jointed shield tunnel lining in fractured surrounding rock, research on the bearing capacity evolution law of staggered jointed shield tunnel was carried out, in consideration of surcharge loading and lateral unloading conditions. Firstly, a simplified simulation method for joints without transferring cushions was put forward based on the equivalence principle of stiffness. The rationality and applicability of the proposed method were verified by comparing data with measured values in related literature. Secondly, numerical simulation on the bearing capacity of the tunnel structure was performed on the basis of the simplified simulation of the joint and load structure method. The relationship between bearing state and sectional deformation of segments was analyzed. Finally, according to critical points of the bearing state of segments, the structure safety classification method and deformation control indicators for shield tunnel were proposed. The results show that the yielding order of segment bearing members is different under two conditions. Under the surcharge loading condition, the yielding order is steel bars at the inside of the vault or arch bottom, and then concrete at the inside of the haunch. However, when it comes to lateral unloading condition, the yielding order is longitudinal joint bolts at the vault or arch bottom, steel bars at outside of the haunch, steel bars at the inside of the vault or arch bottom, and bolts at the haunch. Considering the durability, bearing security and reinforcement time of the tunnel structure, controlling values of ellipticity for deformation of segments under surcharge loading conditions are 0.712%, 1.694%, 2.156% respectively, and controlling values under lateral unloading condition are 0.876%, 1.873%, 2.757% respectively.
