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