为了研究不同开挖尺寸和围岩节理组倾角对隧道开挖变形稳定的影响，应用UDEC程序，通过一些假设，设定计算域内包含有水平垂直节理组（0°-90°）和倾斜节理组（45°-135°）2种计算情况，对硐室不同开挖尺寸下围岩的变形稳定情况进行数值模拟。结果表明： 1）水平垂直节理组岩体中围岩变形随硐室开挖尺寸增大先缓慢增加，后呈指数形式急剧增加且失稳，围岩失稳表现为贯穿地表的拱部上方岩体整体塌落； 2）倾斜节理组岩体中围岩变形随硐室开挖尺寸增大先缓慢增加，后急剧增大且失稳，围岩失稳表现为拱部围岩局部塌落； 3）倾斜节理组岩体中硐室开挖后变形比相应水平垂直节理组的要大。 

In this paper, numerical simulations are made to study the influence of different excavation sizes and different joint set dip angles on the deformations of tunnels excavated in fractured rock mass by using the code of UDEC. It is assumed that there are two types of joints, i.e., joints with horizontalvertical dip angles (0°-90°) and joints with inclined dip angles （45°-135°）, in the influenced domain. Conclusions drawn are as follows: 1) The deformation of the surrounding rocks of tunnels in rock mass with horizontalvertical joint sets grows slowly as the excavation size of the tunnel increases before the deformation grows dramatically and failure occurs. The failure takes the form of integral collapse of surrounding rocks above the crown toward the ground surface; 2) The deformation of the surrounding rocks of tunnel in rock mass with inclined joint sets grows slowly as the excavation size of the tunnel increases before the deformation grows dramatically and failure occurs. The failure takes the form of local collapse of surrounding rocks at the crown; 3) The deformation of the tunnels excavated in rock mass with inclined joint sets is larger than that of the tunnels excavated in rock mass with horizontalvertical joint sets. 