Comparative Study on the Effect of Advanced Reinforcement Range of Fiberglass Bolt in Large Deformation Tunnel Face
The instability of the tunnel face is an important factor that induces the large deformation of the broken rock tunnel.The advance reinforcement of the tunnel face with fiberglass bolts has a positive effect on stabilizing the tunnel face,but its reasonable reinforcement range is currently lacking in research.Aiming at the problem of large deformation control in the construction of broken rock mass tunnel,the field test and analysis of the axial force of the bolt are carried out by setting different fiberglass bolt reinforcement range and length,and the reinforcement effect and work efficiency are compared.The results show that:(1)the two kinds of fiberglass bolt reinforcement range can effectively control the stability of the tunnel face,and then effectively control the large deformation of the tunnel.(2)When the reinforcement range of fiberglass bolt is large and the length is long,the axial force of the bolt is large,and the corresponding reinforcement range is small and the length is short,the axial force of the bolt is small,the main reason is that the reinforcement range is extensive,the long reinforcement stiffness is considerable and the load is large.(3)The upper step part of the three-bench method adopts a 9-meter fiberglass bolt with an overlapping length of 3-meter,which can effectively control the stability of the tunnel face and has high efficiency.
advanced reinforcement of the tunnel faceaxial force of fiberglass boltreinforcement parameteradvanced reinforcement effect
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