<p>As the construction of deepwater bridges has extended to longer spans, improving the construction efficiency and economic viability of large-diameter deepwater foundations has become critical. In this study, a hexagonal deep-water bridge foundation, termed a “hexagonal closed-diaphragm walls” (HCDWs), is introduced. Indoor model experiments are conducted to analyse the behaviour of HCDWs and the surrounding soil during the settlement process, with a focus on evaluating their bearing capacity. ABAQUS finite element software is used to simulate the settlement processes of HCDWs, and the effects of the variations in the number of grids and grid side lengths on the bearing capacity are examined. The data indicate a decreasing trend in the stress distribution along the pile’s length, with increased stress at the base. The effective lateral soil pressure range extends to three times the pile’s diameter. An increase in the grid number does not linearly enhance the load-bearing capacity; multiple grids tend to reduce this capacity. The external friction resistance predominantly occurs in the upper pile regions, whereas the internal resistance is concentrated towards the bottom. The external resistance zone exceeds the internal resistance zone and more significantly contributes to the pile support. Comparative loading tests on HCDWs with two, three, four, and five grids yield bearing capacities that are 1.84, 2.68, 3.51, and 4.39 times greater than those of single-grid HCDWs, respectively; these results demonstrate that the bearing capacity does not scale linearly with the grid number because the “grid chamber effect” decreases as the grid size increases.</p>