某水电站3#尾水洞衬砌混凝土裂缝调查与分析

Investigation of Cracks in Concrete Lining at No.3 Tailrace Tunnel of a Large Scale Hydroelectric Station

:某水电站共4条尾水洞,圆形断面,衬砌后直径为11.3m,每条长度均在300m以上,平均水平投影长度约316.9m。围岩以Ⅳ、Ⅴ类为主,产状平缓,层间剪切带发育,岩层软硬相间,成洞条件差。尾水洞施工是该电站施工难度最大、地质条件最复杂的项目。3#尾水洞在衬砌混凝土浇筑后,混凝土洞壁出现了多条纵向裂缝。通过对裂缝进行宏观调查、裂缝变形和收敛观测,系统分析了裂缝产生的原因,认为隧洞围岩应力调整是导致衬砌混凝土产生裂缝的主要原因。提出了加强观测、加固未开挖段围岩、填充裂缝的建议。3#尾水洞衬砌混凝土经过加固后,已于2007年安全运行。

There are four tailrace tunnels of a large scale hydroelectric station. Each tunnel has a length of more than 300m and 11.3m in diameter after lining thereof. The tunnel excavation by drilling and blasting is very difficult because the surrounding rock is a type of stratified sedimentation composed of inter - bedded stratum of weak and hard layers in which cracked shear bands are well developed. A few longitudinal cracks developed in concrete lining wall at No. 3 tailrace tunnel after construction. By investigation of the cracks and monitoring of surrounding rock deformation of the tunnel, causes of cracking were discussed in detail. Surrounding rock stress redistribution is the key factor for cracking in concrete lining wall. Measures such as investigation of the cracks, monitoring of surrounding rock delormation of the tunnel, reinforcing surrounding rock of the tunnel, filling the cracks are suggested.