基于FLAC^(3D)的含软弱裂隙带隧道围岩稳定性研究

Study on Surrounding Rock Stability of Tunnel with Soft Fissure Zone Based on FLAC^(3D)

以云南兴隆隧道1号斜井为工程背景,针对有限长裂隙带对隧道围岩稳定性的影响问题,采用FLAC^(3D)进行数值模拟,分析不同倾角和宽度的裂隙带对围岩竖直位移的影响规律,并进行量化评价。结果表明:(1)随着裂隙带与中心线夹角的增大,上下台阶开挖过程中最大竖直位移变化规律大致相同,均在夹角为30°时达到最大值,但最大竖直位移差值逐渐增加;(2)随着夹角的增大,影响区域由裂隙带附近逐渐转为隧道上方大面积围岩,形状由三角形逐渐转变为帽状,面积先增大后减小,最大影响区域面积为62.70 m^(2);(3)随着0°夹角裂隙带的宽度增大,竖直位移先迅速增加,后趋于平缓,而影响区域面积呈直线增加;(4)提出以竖直位移增量和影响区域大小来量化裂隙带对隧道围岩的影响,以直观反映裂隙带引起的局部失稳和大范围变形。

The No.1 inclined shaft of Xinglong Tunnel in Yunnan Province was taken as the engineering background.Aiming at the influence of the finite-length fissure zone on the surrounding rock stability of the tunnel,FLAC^(3D) numerical simulation was used to analyze the influence law of the fissure zone with different dip angles and widths on the vertical displacement of the surrounding rock,and then quantitative evaluation was carried out.The results are concluded as follows.Firstly,as the angle between the fissure zone and the centerline increases,the maximum vertical displacement during the excavation of the upper and lower steps is approximately the same.The vertical displacement reaches the maximum at an angle of 30°,but the difference of the maximum vertical displacement increases gradually.Secondly,with the increase of the angle,the affected area gradually changes from the vicinity of the fissure zone to a large area of surrounding rock above the tunnel,and the shape gradually changes from a triangle to a hat shape.The area of the affected zone increases first and then decreases,and the maximum area is 62.70 m^(2).Thirdly,as the width of the fissure zone with 0°angle increases,the vertical displacement first increases rapidly,and then flattens out,while the area of the affected zone increases linearly.Fourthly,the increment of vertical displacement and the size of the influence area are proposed to quantify the influence of the fissure zone on the surrounding rock of the tunnel,which can comprehensively consider the local instability and largescale deformation caused by the fissure zone.