Field test on horizontal bearing characteristics of large-diameter PRC pipe piles installed with pre-drilled inserted method

To study the horizontal bearing characteristics of large-diameter prestressed reinforced concrete (PRC) pipe piles installed with pre-drilled inserted method, the field static horizontal load tests were conducted on PRC pipe piles with an 800 mm diameter. The differences in displacement, internal forces, and proportional coefficient of foundation resistance coefficients of PRC pipe piles with pre-drilled inserted method and hammer-driven method were compared. The bearing mechanisms of PRC pipe piles with the two methods were also analyzed. The results show that compared with hammer-driven pipe pile, the horizontal critical load of pre-drilled inserted pipe pile increases by 36.1%. Their ultimate load is similar. Under the critical load, the rotation point of the pile shaft is 7.5 m for hammer-driven pipe pile and 5.5 m for pre-drilled inserted one. The depths of the maximum bending moment section and the maximum soil resistance section coincide, being 5.1 m for the hammer-driven pipe pile and 3.1 m for pre-drilled inserted one. When the horizontal load is less than the critical load, the pre-drilled inserted pipe pile exhibits smaller bending moments and greater lateral soil resistance than the hammer-driven one. The proportional coefficient of foundation resistance coefficients of PRC pipe pile with the two methods exceeds the recommended values in codes, with the pre-drilled inserted pipe pile showing more significant improvement. The m-method demonstrates good applicability in calculating horizontal load effects for pre-drilled inserted pipe pile, but is unsuitable for hammer-driven pipe pile. During the implantation of pre-drilled inserted pipe pile, the upward migration of mortar along the borehole wall fills and penetrates the soil. The bonding capacity between the mortar and soil is enhanced, the horizontal resistance of the foundation soil is increased, and a better displacement control capability is provided compared to hammer-driven pipe pile, indicating a promising application potential in structures with strict displacement requirements, such as bridges.