Abstract: A road project in Yunnan is part of urban special expressway, whose route in the vicinity of K10+520 is close to a 220 kV high-voltage transmission tower. The excavation of the subgrade poses a great threat to the safety of high-voltage transmission tower, and the construction risk is high. In order to ensure the safety of high-voltage transmission tower when excavating the subgrade, the scheme of sheet-pile wall in the paper was selected as the best from the angle of subgrade protection. The deformation observation of tower foundation was carried out in the construction. It is shown that sheet-pile wall can effectively control the accumulation settle-ment and uneven settlement of the tower foundation in subgrade excavation, and the tower deformation is in the allowable ranges. The use of sheet-pile wall has ensured the safety of high-voltage transmission tower, meanwhile, it verifies the rationality and feasibility of the scheme.

Key words: close to, high-voltage transmission tower, subgrade protection, sheet-pile wall, settlement