Mechanism of reinforcement of squeezed branch piles for deep soft foundation based on load bearing capacities

To address the layout of squeezed branch (SB) piles in deep soft soil, a 3D numerical model is established based on the single pile static load tests on the SB pile application project in Shantou soft soil area. The load sharing characteristics and the branch-soil interaction mechanism are investigated during the settlement development. The results show that the load sharing ratio at the pile tip of the SB piles that do not penetrate through deep soft foundation is 19.6%, significantly lower than that of straight piles. The group efficiency η_g of the SB piles is correlated to the number of piles N and pile spacing S_p, with an optimal spacing of 8d recommended for the SB piles in deep soft soil regions. The tip of branch, particularly the lower branch, can transfer a considerable load to the surrounding soil under the ultimate settlement conditions. The inter-branch spacing S_b affects the load bearing of piles by altering the properties of soil stratum of branches.