Study on the Stability of Shallow-Buried Bias Voltage Neighbourhood Tunnel and Slope Under Different Excavation Methods
[Purposes]The interaction between the neighbourhood bias tunnel and the side slope is often encountered in the construction of the tunnel,which may lead to tunnel collapse and slope instability.Therefore,it is necessary to reinforce the two in time during the construction process,especially the shallow buried neighbourhood bias loess tunnel.[Methods]Based on the project background of Baishi No.1 Tunnel,a supporting project of Lanzhou Hub introduced by Zhonglan Passenger Dedicated Line,the stability of small clear distance tunnel under different excavation methods and construction se-quence is studied by numerical simulation.[Findings]The results show that the plastic zone formed by shallow-buried unsymmetrical tunnel excavation with small clear distance is connected with the poten-tial sliding surface of the slope,which is easy to collapse the tunnel and cause landslide disaster near the slope.The excavation method of three-step temporary cross brace has the smallest disturbance range to surrounding rock,and the slope stability safety factor obtained by excavating the tunnel near the mountain is larger,which is more conducive to the safety and stability of the small clear distance tunnel and slope.The excavation method of three-step temporary cross brace makes the temporary cross brace and lining share the load,which can restrain the deformation of surrounding rock of tunnel vault and inverted arch to the maximum extent,and then ensure the construction safety.[Conclusions]The corresponding reinforcement suggestions are put forward for the stability of rock pillars in small clear distance tunnels.The research results can provide reference for similar shallow-buried tunnels with small clear distance.
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