Abstract: This paper presents a case history of a deep excavation supporting system that had the combination of sloped ground, soil nailing and soldier pile and lagging wall in Qinghai High Plateau. The groundwater level control was critical to the success of this project due to the excessively large thickness of the layer layers which has a high groundwater level, large permeability and high potential of occurring of quick sand during the construction. Methods that are feasible for the sealing, collecting water and dewatering were compared and the point well method was selected for this project. The design and construction aspects of the point well techniques are introduced in the paper.

Key words: High Plateau Environment, Excessively Thick Sandy Layer, Foundation Excavation, Construction Safety