Calculation method for the ultimate bearing capacity of pressure-cast-in-situ pile with spray-expanded frustum

Abstract

In this paper, the new type of Pressure-cast-in-situ pile with spray-expanded frustum (PPSF) developed by the authors is composed of pile body, ribbed plate, and expanded body with double frustum. The PPSF has the advantages of high bearing capacity, small settlement, high construction speed, and significant economic and environmental benefits. To evaluate the ultimate bearing capacity of PPSF, a calculation method is proposed considering the special shape of PPSF. The ultimate bearing capacity of PPSF is considered as the sum of three parts, e.g., the ultimate bearing capacity of expanded body with double frustum, the ultimate skin friction of pile body, and the ultimate end resistance of pile base. The failure mode of the soil around the expanded body with double frustum is described based on the Meyerhof’s bearing capacity theory. The calculation formula for the ultimate bearing capacity of the expanded body with double frustum is established using the sliding block balance method. The rationality of the calculation method is verified by three cases.