Study on Uplift Bearing Characteristics of Gravitational Reinforced Composite Suction Caisson Foundation

Suction caisson foundations are often subjected to vertical pullout loads, where the uplift bearing capacity of caisson is only composed of the internal and external friction and caisson weight under the drainage condition, hence the uplift bearing capacity is usually small. However, there is no corresponding bearing capacity improvement technology research. So a new suction caisson foundation, gravitational reinforced composite suction caisson foundation, is proposed to solve this problem. The uplift bearing capacity of the gravitational reinforced composite suction caisson foundation and the shearing characteristics of caisson-cement soil interface were studied through the model test and pushout test. The test results show that the uplift bearing capacity of the gravitational reinforced composite suction caisson foundation is much higher than the uplift bearing capacity of the traditional suction caisson foundation. And the uplift bearing capacity increases gradually with the increase of additional load and reinforcement range. The interface shear strength of caisson-cement soil will increases with the increase of normal stress and cement penetration ratio. The ring rib width is wider, the area of the shear zone above the ring rib is larger. The bearing capacity composition and the calculation method of the interfacial shear strength are proposed for analyzing the uplift bearing characteristics of the gravitational reinforced composite suction caisson foundation. It can provide a reference for the engineering design of the gravitational reinforced composite suction caisson foundation under vertical load.