Abstract:

A simplified analytical approach was proposed to study on the interaction of single pile-soil-cap (SPSC)under cyclic loading in layered soils, combined with the theory of Mindlin plate theory and elastic foundation model, as well as the law of load transfer of single pile. At first, we established the stiffness matrixes for interaction of SPSC and predicted the accumulative settlement of the single pile with cap and variation of SPSC global stiffness through employing attenuation of compressive modulus. Then, on the basis of this, we carried out cases verification and parameters analysis. The results show that, calculated data by the method in this paper is well consistent with those by Butterfield method; furthermore, the global stiffness of the SPSC is significantly greater than that of the single pile because of the addition of the pile cap, and the increase of elastic modulus of the pile can obviously strengthen the global stiffness; meanwhile, there exists an optimum value range of the length of a pile for a given diameter, and the increase of the length of pile has less influence on the global stiffness of the SPSC and the bearing load ratio of the cap when the ratio of length to diameter of pile is larger than a determined value; finally, the global stiffness of the SPSC gradually increased with the cyclic count until the stiffness is up to a stable value.

Key words: single pile-soil-cap, cyclic loading, foundation of layered soils, global stiffness, Mindlin plate theory