以贵州某水电站无压引水隧洞加固工程为例,针对弱膨胀性泥岩导致的隧洞侧墙变形开裂、顶拱岩块脱落、底板隆起等工程病害,结合工程所在区域的地质特点,通过试验和地质雷达等手段对隧洞围岩变形特征进行分析,明确了隧道围岩长期遭水浸泡,膨胀性围岩遇水膨胀是引发隧洞病害的主要诱因。采用三维数值模型,对隧洞膨胀性围岩遇水膨胀导致的隧洞侧墙应力应变分布特征进行模拟。拟定以排水、隔水为主,同时采用锚杆加固、对侧墙变形严重区段分块拆除重建的工程修复方案,并提出在实际施工过程中应注意隧洞侧墙逆止阀安装、隧洞侧墙拆除重建等施工工艺要求。本隧洞修复工程最终取得良好的实际运用效果。

With the reinforcement project of non-pressure diversion tunnel of a hydropower station in Guizhou as background, this research aims at the engineering diseases such as deformation and cracking of side wall of tunnel, detachment of rock blocks from tunnel vault and upheaving of tunnel floor caused by weak expansive mudstone. According to the geological characteristics of the study area, we analyzed the deformation of surrounding rock by means of tests and geological radar, and found that the swelling of rock triggered by long-term water immersion is the main cause of engineering diseases. Moreover, by simulating the stress and strain distribution of sidewall in 3-D model, we proposed a restoration scheme involving drainage and water insulation, supplemented by anchor reinforcement and partition demolition in severely deformed sidewall area. In addition, we put forward some requirements for construction techniques, such as the installation of check valve on sidewall and the demolition and reconstruction of sidewall. The restoration project has finally achieved good practical result.