Abstract
AbstractFooting foundations are sometimes built on sloping grounds of natural sand which is highly anisotropic. The anisotropic mechanical behaviour of sand can significantly influence the bearing capacity of a foundation and the failure mechanism of its supporting slope. Neglecting sand anisotropy may lead to overestimated bearing capacity and under‐design of foundations. A numerical investigation on the response of a supporting slope under a strip footing is presented, placing a special focus on the effect of sand anisotropy. A critical state sand model accounting for fabric evolution is used. The nonlocal method has been used to regularize the mesh‐dependency of the numerical solutions. Predictions of the anisotropic model on the bearing capacity of strip footings on slopes are validated by centrifuge test data on Toyoura sand. Compared to the centrifuge test data, an isotropic model may overpredict the bearing capacity of the footing by up to 100% when the model parameters are determined based on test data on a horizontal bedding plane case. When the isotropic model parameters are determined based on test data where the bedding plane is vertical, the predictions of bearing capacity can be improved for some cases but the settlement at failure may be significantly overestimated. The soil body tends to move along the bedding plane upon the footing loading due to the non‐coaxial strain increment caused by fabric anisotropy. The slip surface appears to be deeper with lower bearing capacity when the preferred soil movement direction caused by bedding plane is towards the slope.
Highlights
Engineered structures may frequently use shallow foundations to build on cohesionless sloping grounds
Good candidates include early sand models accounting for the inherent fabric anisotropy (e.g., Pastor[26]; Pastor et al.[27]; Li and Dafalias[28]; Dafalias et al.[29]; Manzanal et al.30) and recent models that account for fabric and fabric evolution.[23,31]
The recent anisotropic models have been established within the anisotropic critical state theory, in which the effect of fabric and fabric evolution on sand behaviour is considered in conjunction with a well-defined critical state accounting for fabric anisotropy.[32]
Summary
Engineered structures may frequently use shallow foundations to build on cohesionless sloping grounds. These structures include railway tracks, retaining walls, transmission towers, and bridge piers.[1,2,3] The deformation and failure mechanism of these foundations is affected by the mechanical behaviour of the soil. Natural soils are commonly anisotropic due to gravitational deposition and compaction, and it is well recognized that the fabric anisotropy has a significant influence. Int J Numer Anal Methods Geomech. 2021;45:1526–1545
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