Finite element models for suction bucket foundations with and without cruciform inner clapboards and solid embedded circular foundation in soft soil were established in order to investigate effects of cruciform inner clapboards on uniaxial bearing capacities and failure modes of suction bucket foundation. A large number of finite element calculations and analyses have been carried out to obtain uniaxial bearing capacities of the above-mentioned 3 foundations with different embedment ratios and soil shear strengths by using displacement load method. The results show that the uniaxial bearing capacities of suction bucket foundation are nearly not affected by inner clapboards in uniform soft soil

and the failure modes of the above-mentioned foundations are similar. When the shear strength of soft soil is heterogeneous

uniaxial capacities except vertical capacities of suction bucket foundations with cruciform inner clapboards and low embedment ratios

especially for moment capacities

increase obviously due to cruciform inner clapboards. Meanwhile

the uniaxial horizontal and moment capacities of suction bucket foundation with cruciform inner clapboards increase with the increment of the unevenness index of soil shear strength and are nearly equal to those of solid embedded circular foundation. Failure mechanisms of suction bucket foundation without inner clapboards and with low embedment ratios built in heterogeneous soft soil are obviously different from the other two foundations. Simplified calculating formulas were proposed to predict uniaxial capacities of suction bucket foundation with cruciform inner clapboards.