Abstract: The case history of a deep excavation using a pileanchor supporting system is presented in this paper. The excavation support system was constructed in sandy cobble soils and was instrumented. The earth pressures, the stress in the piles and the tension force in the anchors were monitored during the excavation. The results indicated that the earth pressures acting on the piles were only 1/6 to 1/10 of the atrest earth pressure. The excavation depth had minor impact on the steel wales. The stress recorded in the pile rebar was only 16.8% of the design strength. The stress loss in the prestressed anchors was observed immediately after the pretension. These data provide valuable information for similar deep excavations in the Chengdu area.

Key words: Sandy Cobbles, PileAnchor Supporting Structures, Filed Measurements