Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation

TY - GEN

T1 - Design of plate and screw anchors in dense sand

T2 - 7th International Symposium on Deformation Characteristics of Geomaterials (IS-Glasgow 2019)

AU - Cerfontaine, Benjamin

AU - Knappett, Jonathan

AU - Brown, Michael

AU - Bradsaw, Aaron S.

N1 - This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 753156.

PY - 2019/6/25

Y1 - 2019/6/25

N2 - Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.

AB - Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.

UR - https://www.scopus.com/pages/publications/85069715905

U2 - 10.1051/e3sconf/20199216010

DO - 10.1051/e3sconf/20199216010

M3 - Conference contribution

SN - 978-2-7598-9064-4

VL - 92

T3 - E3S Web of Conferences

SP - 1

EP - 6

BT - 7th International Symposium on Deformation Characteristics of Geomaterials (IS-Glasgow 2019)

A2 - Tarantino , A

A2 - Ibraim , E

PB - EDP Sciences

Y2 - 26 June 2019 through 28 July 2019

ER -