Experimental study of stability of interlocking L-shaped caisson on soft soil interlayer ground

The interlocking L-shaped caisson, as a new type of caisson structure, exhibits enhanced performance under complex marine loading conditions. This structure shows significant potential for applications in marine infrastructure, including deep-water port terminals, breakwaters, and artificial islands. The feasibility of replacing the conventional L-shaped caisson (CLC) with the proposed interlocking L-shaped caisson (ILC) is investigated through indoor loading model tests. The paper investigated the effects of filling materials, foundation types, and load forms on the stability of caisson docks formed by adjacent ILCs within a hexagonal prism cavity. Compared to CLC quay wall, the ultimate bearing capacity of the ILC quay wall, when pinned by gravel or concrete blocks, increased by 15.5% and 20.1% under strip load. The ILC quay wall with concrete block interlocking reinforcement exhibits superior load-bearing performance. When the sand ground is replaced with a soft soil interlayer ground, the ultimate bearing capacity of the ILC quay wall decreases. The ultimate failure mode of the ILC quay wall shifted from overturning to overall instability failure, with the failure surface changing from arcs and straight lines to multi-segmented lines. When strip loads are replaced by concentrated loads with a smaller range of action, the integrity of the ILC quay wall deteriorates, its ultimate bearing capacity significantly decreases, and the settlement of the backfill soil surface near the caisson increases.