Failure Mechanism Of Spudcan In Spatially Random Soils

Spudcan foundat ions are a significant part of operation platforms with the self-elevat ing jack-up for offshore oil and gas drilling which tradit ionally were installed in shallow water or deeper. Generally, the geometry of spudcan was cone and it can penetrate in soft soil by up to 3 diameters to achieve adequate bearing capacity.Although research on the failure mechanisms and bearing capacit y o f spudcan foundat ions have been conducted in homogeneous soil or layered uniform soil, the effect of the spatial variabilit y in soil strength on the spudcan response is still unclear. This paper adapted finite element method combining with Monte Carlo simulat ion theory to present the method about failure mechanisms and bearing capacit y of a spudcan found at ion embedded in spat ially varied seabed soils.This paper demonstrates that the stochast ic properties of the seabed soil, which combined the simulat ion of seabed soil spatial variabilit y of random field theory with the finite element theory to study the spudcan foundat ion bearing capacit y and failure mechanism. The geometry of spudcan was modeled as simplified shape according to the real foundation. The validat ion of the research methods were doned by comparing the simulat ion results with the exist ing literatures. Results show that the bearing capacit y of the foundation in the spat ially random soil is determined by the length of the path and the of the undrained shear strength of the soil in the shear plane.The stochast ic finite element method is adapted combining with the Monte Carlo simulat ion method to analyze the influence of horizontal and vertical spat ial variet y on the vert ical bearing capacit y and failure mechanism. This paper further studies the influence of isotropy and anisotropy of the soil on the spudcan foundation. The results showed that with the increase of the anisotropy of soil and spudcan on spat ially random soil bearing capacit y becomes smaller. When the horizontal spatial correlat ion length of the spat ially random soil is three t imes of the spudcan width, the Coefficient of Variation of the bearing capacit y of the spudcan is decreased with the increas ing of spatial Variabilit y. When the vert ical correlat ion length of the spatially random soil is 3 m, the Coefficient of Variat io n of the bearing capacit y of the spudcan is increased with the increase of spatial variabilit y.This paper invest igates the safet y factor and the failure probabilit y of the spudcan foundat ion in the spatially random soil. Results show that when spat ial correlat ion length of the spat ially random soil is three t imes the width of foundation. With the increase of the spat ial variabilit y, the failure probabilit y o f spudcan becomes larger, while the corresponding safet y factor of specific failure probabilit y decreases wit h t ime. When the vert ical correlat ion length of the spat ially random soil is 3 m, the failure probabilit y of the spudcan foundat ion becomes smaller with the increase of the spat ial variabilit y, but the safety factor of the corresponding failure probabilit y becomes larger gradually.