The construction of waterproof courses commonly designed at present in outside waterproofing of underground works with PVC has some defects which can be overcome by adopting dividing intercepting method.

Taking the defect treatment of Shidaoshan tunnel and Gaoshan tunnel on Hefei-Caohu-Wuhu highway as example,the author presents the methods,principles,construction workmanship and attention points of the treatment of the seepage/leakage defects of tunnels by means of water intercepting trench method,which can provide reference for similar works in the future.