Upper bound solution for ultimate bearing capacity of suction caisson foundation based on Prandtl failure mode

In order to study the upper bound solution of the uplift ultimate bearing capacity of suction caisson foundation, the viewpoint of reverse bearing capacity and the reverse Prandtl failure mode were introduced for study. The reverse Prandtl failure mode means that the active area of Prandtl failure mode becomes the passive area and the logarithmic spiral direction was opposite. At the same time, the relationship between the upper bound solution and cohesion, internal friction angle, soil pressure and friction coefficient were analyzed. Then, the upper bound solution was calculated by using the Matlab calculation program and was compared with the previous experimental data and other upper bound solution. The results show that the proposed equations are verified by the corresponded test results. And the upper bound solution agrees reasonably well with the other test results. The error between upper bound solutions and the experimental values are basically controlled to be less than 40%, with the maximum error being 44%, and the minimum error being 3%. It can be proved that the failure mechanism is reasonable and more consistent with the actual force condition. © 2019, Central South University Press. All right reserved.