Abstract:
Concrete-filled steel tube rock-socketed piles are a new type of deep foundation in deep water and shallow overburden environments, and are widely used in the construction of deep water wharves in inland rivers. In view of the combined bearing characteristics of steel-concrete for concrete-filled steel-filled piles under cyclical horizontal loads such as ship impact force, wave force and current force, three models of large-scale concrete-filled steel tube rock-socketed piles of 1∶7.3 were made. At different heights of the pile body, strain measuring points were arranged on the outer side of the steel tube, the corresponding inner concrete block and the built-in stressed steel bars, with 18.0, 22.5 and 27.0 kN as the cyclic amplitude, to develop the steel-concrete joint bearing law of the concrete-filled steel tube rock-socketed piles test. The results show that the steel-concrete strain of the pile body satisfies the four stages of linear growth, steady fluctuation, severe vibration and sharp decline, and each stage accounts for 8.66%, 79.66%, 6.06% and 5.62% of the fatigue life; the strain of steel pipe on that outside the same pile section is quite different from that of concrete on the inside, and the maximum is more than 80% of the concrete strain. The built-in steel bars and the concrete always maintain strain coordination, and the maximum strain difference does not exceed 20% of the concrete strain; at the top of the pile with a small bending moment, the bending moment of pile body is mainly borne by inner concrete, which accounts for more than 70%. Along the pile, the ratio of the section bending moment borne by the steel pipe gradually increases. At the bottom of the pile, the proportion of the two bending moments is approximately equal. The steel pipe and the concrete are subjected to bending. Simultaneously, at the same pile section, the greater the cyclic amplitude, the earlier the two will reach the bending coordination state.