丹巴水电站引水隧洞衬砌结构安全与围岩稳定性分析

依托丹巴水电站引水隧洞工程,研究锚杆和衬砌对围岩稳定性的影响,进行了不同埋深下隧洞衬砌厚度的比选和衬砌的安全性分析、配筋和裂缝宽度验算等,考虑了不同衬砌施加时机对隧洞受力及位移的影响。研究发现,锚杆支护可使围岩塑性区分布更加均匀,受力更加合理,可较好的控制围岩变形;衬砌内最大压应力值随着埋深增加而增大,随着衬砌厚度增加而降低;提出了有效减压区,应在有效减压区选择衬砌厚度,衬砌厚度选1.5m为宜;在最危险工况下,给出了合理的配筋设计方案;经过不同位移量和不同模型下衬砌安全性的对比分析,衬砌加固选择85%的位移预留量,围岩的变形量和最大控制内力都可得到明显的控制。

Safety of lining structure and stability its surrounding rocks for the diversion tunnel of Danba Hydropower Station

The influences of bolt and lining on the stability of its surrounding rock are investigated in this study for the diversion tunnel of Danba Hydropower Station.The thickness of tunnel lining under different buried depths are investigated,and the safety of lining under different working conditions is analyzed.The reinforcement and the crack width are checked,and the influences of different lining application time on the force and displacement of the tunnel are taken into consideration.It is found that the bolt supporter can make the distribution of the plastic zone of its surrounding rocks more uniform and the force is more reasonable,which could control the deformation of the surrounding rock better.The maximum compressive stress in the lining will increases with depth,and decreases with the lining thickness.An effective decompression zone is proposed,which should be selected within the effective decompression zone.The lining thickness is preferred at 1.5 m.In the most dangerous conditions,a reasonable design scheme of reinforcement is given.By comparing and analyzing the safety of lining under different displacement and different models,85% displacement reserve is chosen for lining reinforcement,and the deformation and maximum internal force of surrounding rock can be obviously controlled.