Analysis of the effect of pullout rate on the tensile capacity of suction caisson anchors in sand using a three-dimensional displacement method

There has been little analytical research work to clarify the influence of the pullout rate on the ultimate capacity of suction caisson anchors subjected to vertical tensile (V), horizontal (H), and moment (M) loads in soils. In this study, an analytical approach is proposed by employing a three-dimensional displacement method to elucidate the effect of the pullout rate on the ultimate vertical tensile, horizontal, and moment capacities of suction caisson anchors in sands. The vertical displacement of the inside and outside soils adjacent to the skirt of the caisson is obtained from considering the vertical equilibrium of an annular element of the skirt via vertical tractions inside and outside the skirt of a caisson subjected to a vertical tensile load. An appropriate bearing capacity equation for predicting experimental results of suction caisson anchors in sand is proposed. Reasonable agreement is found between the results obtained from laboratory and field tests and those predicted by the present method, comparing the relationships among the capacity, suction, and displacement of suction caisson anchors in sand subjected to inclined tensile loads with various pullout rates. Failure envelopes in the H–V plane are shown taking into account the effect of the pullout rate on the ultimate inclined tensile capacity for a suction caisson anchor in sand.