An analytical solution for the load-settlement relation of hollow composite piles with ultra-large diameters

Abstract

The load transfer mechanism is significantly more complex due to its heterogeneous radial distribution properties. To solve this problem, smart sensors and actuators are the good candidates for the improvement of structural reliability and robustness. This study investigates the load transfer characteristics of hollow composite piles with ultra-large diameters, and finds out the load transfer path. Based on the shear deformation transfer method and the assumptions of no relative slide between hollow pile, grouting body and cement mixing pile interface, a mechanical analysis model of hollow piles with ultra-large diameters-grouting body-cement mixing pile, is then developed. The basic equations of load-settlement relation of piles are deduced from the mechanical equilibrium conditions. Based on the hyperbolic model, the equivalent elastic modulus is introduced to improve the transfer function method. Afterwards, analytical solutions for the load-settlement relation of hollow composite piles with ultra-large diameters are presented. Finally, the analytical solution based on the two methods is compared with the finite element solution in order to verify their rationality and feasibility. The results indicate that under vertical load, the load transfer path to pile side (radial) is as follows: hollow pile → grouting body → cement mixing pile → foundation soil. Moreover, the transfer path of load to pile tip (vertical) is directly transferred to foundation soil, which is consistent with the traditional large-diameter solid pile. Compared with the shear deformation transfer method, the transfer function method can better simulate the nonlinear soil, which is more consistent with the finite element results.