Abstract: To study the influence of the embedding action of diaphragm wall below the bottom of diaphragm wall-gravity anchorage composite foundation on its bearing capacity, two sets of physical model tests of the underground diaphragm wall-anchor combined foundation and the conventional anchor foundation without considering the embedding effect of diaphragm wall-were carried out under the same conditions, relying on the design scheme of new diaphragm wall anchorage at Qingyuan side of Xijiang Super Bridge. The relationship between load and displacement, the distribution of soil pressure and the load distribution are analyzed. The results show that the vertical displacement and horizontal displacement of the combined anchor foundation are obviously smaller than that of the conventional anchor foundation due to the consolidation and fixed effect of the diaphragm wall under the vertical and horizontal loads. Compared with the conventional anchorage, diaphragm wall-gravity type composite anchorage foundation can make full use of diaphragm strength embedded into rock and bearing capacity of deep rock mass. The horizontal displacement can be reduced by about 75% under the design of cable force, which effectively improve the bearing and safety performance. The vertical load can transfer from the ground wall structure to the deep bedrock, which can share the soil pressure on the foundation base, and reduce additional stress and settlement, according to the soil pressure and load distribution law. The comprehensive analysis shows that the contribution for bearing capacity of ground diaphragm wall designed as the anchorage foundation of the retaining structure can be considered in design, when the bottom of underground diaphragm wall is embedded into bedrock.

Key words: underground diaphragm wall-anchor combined foundation, model experiment, fixed effect, load distribution