Peak punch-through capacity of spudcan in sand with interbedded clay: numerical and analytical modelling

Abstract

The presence of a thin soft clay layer inside a bed of sand may significantly reduce the bearing capacity of the sand layer, imposing a risk of punch-through failure. In this paper, finite element (FE) simulations are reported using a hardening soil (HS) model for sand. The FE model has been verified against centrifuge tests involving loose and dense sand layers overlying clay soil. The effects of sand stiffness, foundation roughness, sand friction angle, undrained clay strength, clay strength nonhomogeneity, and sand and clay layer geometries on the foundation peak capacities have been studied. Punch-through failure is initiated with an inclined sand plug being sheared and pushed into the underlying soft clay. During punch-through, the clay layer fails due to significant radial squeezing. Existing analytical models do not capture the combined failure mechanism of sand shearing and clay radial squeezing. A new analytical model is developed to estimate the peak punch-through capacity of a spudcan in sand with an interbedded clay layer, showing improved performance over the current industry guidelines.

Numerical investigation of spudcan penetration in sand with interbedded clay

“…A Poisson's ratio υ = 0.49 was selected to simulate undrained conditions in clay. According to Ullah and Hu [7], the resistance is not significantly impacted by the Poisson's ratio for sand, typically ranging between 0.2-0.4. Therefore, a Poisson's ratio of 0.3 was selected for the sand, which is consistent with common practice [4].…”

“…In the context of sand interbedded with clay, Ullah et al [3] explored the effects of various factors such as the thickness of the top sand layer and clay layer, clay layer thickness, top sand friction angle, and inhomogeneity of clay strength on the peak bearing capacity and failure mechanism, employing the IOP Publishing doi:10.1088/1755-1315/1337/1/012064 2 small-strain finite element method. Nonetheless, the alteration of failure mechanisms during spudcan penetration remained unexplored.…”

Determination of bearing capacity of a sand-mudstone interbedded foundation in Chengdu

“…For the determination of bearing capacity of building foundation, the commonly used"Code for design of Building Foundation Foundation"(Gb50007-2011) [1] is determined, however, the method of determining the bearing capacity of rock foundation is only to calculate the bearing capacity by multiplying the saturated uniaxial compressive strength by the reduction coefficient, which is questioned by many scholars [2,3] , it is difficult to make full use of the bearing capacity of soft rock mass by using only the saturated uniaxial compressive strength of indoor rock to determine its bearing capacity, cause waste. Therefore, this paper combined"Building Foundation Foundation design code"(GB50007-2011).…”

On Cubic Spudcan Deep Penetration in Dense Sand Overlying Non-Uniform Clay

“…Spudcan penetration in strong-over-soft sediments has been addressed by a number of researchers, with particular focus on the mechanism of punch-through failure and methods for predicting the (post) peak penetration resistance and the corresponding depth [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In addition, mitigating measures for possible punch-through failure of spudcans have been explored [21][22][23][24][25].…”