Analysis and Evaluation of the Stability of Surrounding Rock During the Sluicing Sealing Period of the#5 Diversion Tunnel at Wudongde Hydropower Station
For the water conservancy and hydropower projects that adopt diversion tunnels for flood discharge,the temporary diversion tunnels need to be closed and blocked successively during the water storage period,and the flood dis-charge will be shifted to the permanent flood discharge structures after water storage.During the closing and blocking pe-riod of the diversion tunnels,the water level of the upstream reservoir continues to rise.Whether the diversion tunnels can be safely closed and blocked under high water head conditions determines whether the project can store water on schedule and exert its benefits.Taking the Wudongde Hydropower Station on the Jinshajiang River as an example,this paper focuses on the stability and safety of the surrounding rock during the sluicing sealing period of the#5 diversion tun-nel.Three-dimensional numerical analysis methods was used to compare and analyze the geological tunnel sections under Class Ⅳ2 rock conditions and near the F3 fault.It systematically studied the rock mass seepage field,incremental deform-ation of the surrounding rock,stress in the surrounding rock,plastic zones in the rock,stress on anchorage support,and lining stress.Additionally,considering the failure of the lining,the stability of the surrounding rock during the sealing construction period of this tunnel segment was analyze to assess the safety of the tunnel support system.The results indi-cate that the drainage holes in the tunnel body effectively reduced the pore water pressure around the tunnel;The sur-rounding rock generally showed a trend of deformation towards the inside of the tunnel,with minor incremental deforma-tion;The stress distribution in the surrounding rock was adjusted slightly,but overall changes were minimal,with no significant expansion of the plastic zone;The support system was in a normal working condition,with some anchors near the fault experiencing greater stress;The lining was under minor stress,and the reinforcement of the lining met the re-quirements for bearing the stress,suggesting good stability and safety of the surrounding rock during the sluicing sealing period of the#5 diversion tunnel.
diversion tunnelsluicing sealing periodstability of surrounding rocksupport safetythree-dimensional numerical calculationdrainage hole model
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