Abstract: This paper presents a case history of the foundation treatment project of the Huisheng Time Square in east suburban of Chengdu City. Detailed cost comparisons were made between the pressure grouted all flight auger castinplace concrete piles and rotary drilled cast -in-place concrete piles. It was concluded that the grouted auger cast piles is more cost effective in the soft rock with unconfined compressive strength less than 5MPa. Compared with the cast-in-place concrete piles formed by the rotary drilling method, a 17.8% of construction time and a 29% of the construction cost were saved. The selected grouted all flight auger cast-in-place pile were integrity and static loading tested. This paper also summaries the quality control issues.

Key words: pressure grouted all flight auger cast-in-place piles, rotary drilling, foundation treatment, underlying bedrock