中文摘要：

以湖北某高速公路隧道为工程背景,针对IV级围岩,利用有限元程序,通过数值模拟的方式,分析了采用台阶开挖和环形开挖时初期支护结构的变形和应力特征,结果表明：采用环形法所产生的应力和位移总体较台阶法小,从安全的角度考虑,环形开挖较好.此外,在初期支护后,应该对隧道的局部位置进行加强处理,以免出现初期支护的局部破损、降低其整体性.

英文摘要：

This paper gives out the primary support′s deformation behaviour and stress analysis of Ⅳ surrounding rock.Based on the the Dachuan tunnel,it conerns about two diffierent excavation method,namely bench method and loop method,which have been simulated by finite element program.The results show that it is better to choose loop method.Meanwhile,the paper points out some problems which exist universally,and put forward a feasible supporting strategy to improve the structure.All of this provide theoretical base for tunnel′s construction.