中文摘要：

隧道洞口围岩大多为软弱围岩,加之浅埋、偏压等不良地质地形因素的影响,洞口施工过程中易发生边仰坡的滑塌。厦蓉高速公路水都线的瑞坡隧道在进洞后不久就发生围岩失稳,致使仰坡开裂滑塌和洞内支护变形很大。利用FLAC3D软件模拟了隧道施工全过程,从围岩塑性区分布以及位移情况结合现场实际状况分析了隧道仰坡坍塌和支护变形发生的原因,并通过数值模拟优化了CRD法的开挖工序。最后参考数值分析结果结合工程实际提出了有效的治理措施,得到的结论可供今后类似工程参考与借鉴。

英文摘要：

Landslide is easy to occur at the tunnel portal section due to the surrounding rock is weak,and besides,many of the tunnels portal section are shallow and under unsymmetrical pressure.The surrounding rock of Ruipo tunnel in Guizhou province of Xiamen-Chengdu expressway is instability when the tunnel excavated shortly.Analysis of three-dimensional simulation in the excavation process of portal section of Ruipo tunnel is conducted by using the fast Lagrangian analysis of continua in three dimensions（FLAC3D）.Based on the results of plastic zones in surround rocks,deformations in rock and actual situation on site,the causes of tunnel collapse and support deformation are analyzed.Actual tunnel excavation sequence is optimized by numerical simulation.Then the effective remedy measures are proposed and good results are achieved.The analysis results can provide reference for similar engineering.