Abstract: The pressure-cast-in-situ fluid solidified soil pile (PFSSP) is a new type of flexible pile developed by the authors. Compared with traditional cement mixing piles, it has the advantages of stable pile quality and high single-pile bearing capacity. To investigate the bearing characteristics of the PFSSP composite foundation, a plate load test was carried out on the PFSSP composite foundation, and a three-dimensional numerical model of the PFSSP composite foundation was established. The rationality of the numerical calculation results was verified using the field plate load test results, and the influences of the expansion ratio (defined as the ratio of the expanded body diameter to the upper pile diameter), the position of the expanded body, and the lower pile diameter on the bearing characteristics of the PFSSP composite foundation were analyzed based on the numerical calculation results. The research results show that the PFSSP composite foundation can give full play to the core bearing role of the pile body and effectively utilize the bearing potential of the soil mass. Considering the rationality of load bearing, construction feasibility and economic efficiency, the expansion ratio of the PFSSP is preferably 1.4 to 1.5, the optimal position of the expanded body is in the range of 2 to 4 times the upper pile diameter, and the optimal range of the lower pile diameter is 300 mm to 350 mm. The research results can provide a reference for the optimal design of the PFSSP composite foundation.

Key words: pressure-cast-in-situ fluid solidified soil pile, composite foundation, bearing characteristics, numerical simulation, parameter analysis