关键词: 破碎围岩;二次衬砌施作时机;Hoek-Brown强度准则;数值模拟;紫石隧道;

Abstract: In order to determine the optimal construction time of the secondary lining in a tunnel with broken surrounding rock, taking the Zishi Tunnel of Yaan-Kangding Expressway as an example, the Hoek-Brown strength criterion was embedded in Abaqus software and a numerical calculation model was established. Based on this model, the internal forces of the primary support structure and the secondary lining structure of the deep buried section in the IV-class surrounding rock, the deep buried section and shallow buried section in the V-class surrounding rock were numerically simulated and analyzed, and the safety factors of the secondary lining under different displacement release rates of the surrounding rock were calculated. The results showed that when the displacement release rate of surrounding rock reached 90 % and 95 % respectively, the growth of the initial support internal force of the deep buried section in the IV-class surrounding rock and the V-class surrounding rock tended to be gentle. The optimal construction time of the secondary lining in the deep buried section of the IV-class surrounding rock was when the displacement release rate of the surrounding rock reached 90 %. The optimal construction time of the secondary lining in the deep and shallow buried sections of the V-class surrounding rock was when the displacement release rate of the surrounding rock reached 95 %. Under the above conditions, the internal force and safety factor of the tunnel structure could meet the requirements of specifications.

Key words: broken surrounding rock; construction time of secondary lining; Hoek-Brown strength criterion; numerically simulation; Zishi Tunnel