富水软弱围岩隧道穿越断层破碎带的稳定性分析及施工技术

Stability Analysis and Construction Technology of Surrounding Rock of Fault Fracture Zone in Water-rich Soft Surrounding Rock Tunnel

研究了富水软弱围岩隧道穿越断层破碎带围岩稳定性影响问题及施工技术.以国家一带一路重点项目云南临沧临翔至清水河高速公路马家寨隧道工程为依托,通过有限元软件MIDAS GTS NX分别建立不同断层破碎带夹角、倾角的隧道三维有限元模型,对隧道围岩稳定性进行分析,并提出相应处治措施.研究结果表明:拱顶沉降、仰拱隆起及周边收敛均呈现出先增大后减小的现象,说明距离断层越远,对围岩稳定性影响越小;围岩变形的突变范围均随着断层倾角、夹角增大而减小;不同断层倾角、夹角工况下围岩应力均为压应力;断层处围岩应力明显小于周围围岩,围岩应力分布状态发生改变;断层破碎带对富水软弱围岩隧道围岩稳定性影响较大,应加强地质预报并采用全断面超前帷幕注浆堵水方案.

The influence of surrounding rock stability and construction technology of the water-rich soft surrounding rock tunnel through the fault fracture zone were studied.Relying on the National Belt and Road Key Project,Linxiang to Qingshuihe Expressway Majiazhai Tunnel Project in Lincang City,Yunnan Province,through the finite element software MIDAS GTS NX,three-dimensional finite element models of tunnels with different angles and dips of fault fractures were established.The stability of the surrounding rock of the tunnel was analyzed,and corresponding treatment measures were proposed.Research indicates:The settlement of the vault,the elevation of the inverted arch and the convergence of the periphery all show a phenomenon of increasing first and then decreasing,suggesting that the farther away from the fault,the smaller is the impact on the stability of the surrounding rock.The abrupt range of deformation of surrounding rock decreases with the increasing dip angle and angle of the fault.The larger the dip angle of the fault at the vault,the larger is the settlement of the tunnel excavation starting point,while the smaller are the settlement at the end of the tunnel excavation and the maximum settlement of the vault.The larger the dip angle of the fault in the invert arch,the smaller is the starting point of the tunnel excavation,the larger is the value of the elevation at the end of the tunnel excavation,and the smaller is the maximum value of the invert arch.The deformation of the surrounding rock in the tunnel under the condition of fault angle is basically symmetric,and both decrease with the increase of the angle of the fault.The surrounding rock stresses under different dip angles and angles are compressive stresses.The surrounding rock stress at the fault is significantly smaller than the surrounding rock on both sides,and the stress distribution state of the surrounding rock is changed.The fault fracture zone has a great influence on the stability of the surrounding rock of the water-rich and weak surrounding rock tunnel,and geological prediction should be strengthened and a full-section advanced curtain grouting and water blocking scheme should be adopted.