大跨暗挖地铁车站喷锚式主动支护体系应用效果分析

Analysis of Application Effectiveness of Large-Span Tunnel Station with Anchored Active Support System

文中以青岛地铁6号线一期工程石山路站暗挖主体为例,通过调研发现,岩质地层中锚杆作用被严重弱化,导致初支拱架设置过密、喷层过厚、锚杆无法与围岩有效承载等问题突出。文中针对该工程特点,在Ⅲ级围岩段,采用以预应力锚杆+网喷混凝土为主的锚喷式主动支护结构形式,根据数值分析,拱部最大沉降为4.7 mm,边墙最大水平位移为0.2 mm,拱部锚杆轴力约115~126 kN,边墙锚杆轴力约104~109 kN。经现场监测数据反馈,拱顶最大沉降3.2 mm,边墙收敛最大变形约2.4 mm,拱部及边墙锚杆轴力稳定值约100 kN。在硬岩地层中,对预应力锚杆施加预加力,及时恢复围岩三向受力状态,能有效发挥围岩自承能力,控制开挖轮廓变形,保证隧道施工安全。

Taking the excavation main body of Shishan Road Station in Phase I of Qingdao Metro Line 6 as an example,through research,it is found that the anchoring effect in the rocky strata is severely weakened,leading to problems such as overly dense initial support arches,excessively thick sprayed layers,and ineffective load-bearing capacity between anchor rods and surrounding rocks.Based on the characteristics of this project,an innovative anchor-sprayed active support structure mainly composed of prestressed anchor rods and shotcrete is adopted in the Il-level surrounding rock section.According to numerical analysis,the maximum settlement of the arch is 4.7 mm,the maximum horizontal displacement of the side wall is 0.2 mm,the axial force of the arch anchor rod is approximately 115-126 kN,and the axial force of the side wall anchor rod is approximately 104-109 kN.Feedback from on-site monitoring data shows that the maximum settlement of the arch crown is 3.2 mm,the maximum convergence deformation of the side wall is approximately 2.4 mm,and the stable axial force of the arch and side wall anchor rods is approximately 100 kN.By applying pre-tension to the prestressed anchor rods in hard rock formations,restoring the triaxial stress state of the surrounding rock in a timely manner,the self-supporting capacity of the surrounding rock can be effectively exerted,excavation contour deformation can be controlled,and tunnel construction safety can be ensured.