Abstract: To investigate the applicability of the technology and methods of enlarging column tips for cement-soil composite columns, a large-scale excavation and backfilling project in Fujian Province was selected as the research site. Two pipe piles with PHC 400 AB 600 specifications were chosen, and conventional column tips and enlarged column tips techniques were employed, respectively. Field static load tests were conducted to obtain the Q～s curves of the two columns. Strain gauges were installed at different sections to measure the axial force distribution along the column shaft, providing insights into the axial force distribution of the two columns. The results revealed that, under the same column top load, the settlement at the column tip was greater for the columns with enlarged tips compared to the piles with conventional pile tips. Furthermore, the technology of enlarging column tips effectively enhanced the mobilization of the end bearing resistance. Excavation of the soil around the columns after construction, coupled with the use of inclinometers, demonstrated that the adoption of enlarged column tips technology significantly improved the plumbness of the pile shaft.

Key words: Cement-Soil Composite Columns, Enlarged Column Tips, Static Load Test, Pile End Resistance, Plumbness of Column Shaft