Study on the horizontal bearing capacity of solidified soil-tube composite piles

Abstract

The horizontal stiffness of composite piles is an important factor influencing the horizontal bearing capacity of composite piles. However, this factor has been analyzed through field experiences rather than theoretically by other researchers. In this study, a calculation formula for analysis of this factor was deduced through an elastic-plasticity theoretical analysis. The formula was used to investigate influences of solidified soils on the horizontal stiffness and the bearing capacity of composite piles in accordance with stress mechanism under horizontal loads. Then, the differential equation of composite piles deflection under the combined stiffness was achieved. On this basis, a one-way cyclic loading test on six piles was performed on the site. Results demonstrate that solidified soil increases the combined stiffness of composite piles in the deformation process from elasticity to plasticity. The characteristic value and the ultimate value of single-pile horizontal bearing capacity in the composite piles are 1.81-2.62 and 2.00-2.25 times those of tubular pipes, respectively. When the length-diameter ratio of tubular pile is more than 27.5, the single-pile horizontal bearing capacity in the composite piles is less affected with the increase of length-diameter ratio of tubular piles. The accuracy of the theoretical analysis on the factor is further verified by the field test. The conclusions can serve as references for engineering design and further research of composite piles.