Field Study on One-time Pile Construction Method of Helix Stiffened Cement Mixing Piles

The Helix Stiffened Cement Mixing (HSCM) pile is a new type of composite pile. In order to investigate the effects of construction machinery and the one-time pile construction process on the axial bearing performance of HSCM piles, field pile driving tests and axial loading tests were carried out. The pile diameter and bearing deformation characteristics of helical piles, hollow bar micropiles, and HSCM piles were compared and analyzed. The enhancement effect of the one-time pile construction process on the frictional resistance of HSCM piles was discussed. The load transfer mechanism of HSCM piles under different load levels during one-time pile construction was revealed. The test results showed that the one-time pile construction process could form a cement-soil column around the pile core, and an appro-priate increase in the helix plates was beneficial to forming the cement-soil column. When applied in marine soft clay, the bond diameter of HSCM piles could be conservatively estimated to equal the diameter of the helix plates. The axial bearing capacity of HSCM piles is about twice that of helical piles. The one-time pile construction process increased the pile-soil contact area and improved the axial bearing capacity. During loading, the load of HSCM piles was transferred from the helical pile core to the ce-ment-soil and further to the pile-soil contact surface, and its load transfer mechanism was the failure of the pile-soil contact surface.