夹岩水利枢纽工程长石板隧洞施工开挖支护方案优化调整研究

Study on Optimization and Adjustment of Construction and Excavation Support Plan of Changshiban Tunnel in Jiayan Water Control Project

夹岩水利枢纽长石板隧洞4号与5号支洞之间洞段全风化围岩在富水状态下,施工期出现围岩变形松弛、初期支护拱壁收敛缓慢、施工扰动基岩泥化,导致出现支护钢拱架变形、喷混凝土开裂和渗水等问题。文章结合地质揭露成果,按已挖段、试验段和待挖段三个洞段,实施隧洞开挖及支护方案优化设计,并及时调整支护结构参数,成功解决了软岩、强岩溶等地质段围岩抗变形稳定问题。优化调整方案与工程实际匹配性好,支护衬砌结构经济合理。

The completely weathered surrounding rock in the tunnel section between No.4 and No.5 branch tunnel of Changshiban Tunnel in Jiayan Water Control Project shows deformation and relaxation of surrounding rock,the slow convergence of the primary supporting buttress,and argillization of the disturbed bedrock during construction under the condition of rich water,thereby leading to the deformation of the supporting steel arch,the cracking of shotcrete and water seepage,etc.The optimized design of tunnel excavation and support scheme is implemented according to the three excavation sections,namely the excavated section,the experimental section and the to-be-excavated section in the paper according to the geological exposure results,and the supporting structure parameters are adjusted timely.The surrounding rock anti-deformation stability problems in the geological section are successfully solved,such as soft rock,strong karst,etc.The optimization and adjustment plan is well matched with the engineering practice,and the support lining structure is economical and reasonable.