Abstract: The combined foundation of pile-underground diaphragm wall is a new type of foundation, which has the advantages of high horizontal bearing capacity and low cost. The internal force distribution and deformation regularity of the new combined foundation under surcharge are studied by conducting a new type of combinatorial indoor model test. At the same time, a comparison test of the conventional model of the pile-concrete foundation is conducted to obtain the deformation control mechanism of the new combined foundation, for which in order to provide further theoretical and practical basis for the further promotion of this technology. The experimental results show that: (1) The combined foundation has a high bearing capacity relative to the foundation of the pile bearing platform. (2) The combined foundation is mainly driven by the front wall and the lower part of the combined foundation pile is small. (3) The combined foundation and the foundation of the pile are different in the shape of the deformation. The combined foundation is inclined to the stacking side and is in the direction of the whole subsidence due to the larger negative friction resistance. The pile foundation is shifted away from the stacking side. (4) The upper load has less influence on the horizontal bearing capacity of the combined foundation but increases the inclination of the foundation.

Key words: model test, combined foundation, pile, underground diaphragm wall, surcharge