Now showing 1 - 2 of 2
  • Publication
    An investigation of correlation factors linking footing resistance on sand with cone penetration test results
    (Elsevier, 2012-11) ;
    Significant research effort has led to improvements in our ability to estimate the ultimate bearing resistance of footings in sand. These techniques often estimate the footing resistance at relatively large displacements, typically 10% of the footing width, qb0.1. Cone Penetration Test (CPT) design methods typically link qb0.1 and qc through a constant reduction factor, a. A range of a factors for shallow footings have been proposed, some methods suggest that a is constant and while others that it varies with footing width and depth (or stress level). There is a dearth of field data with which to compare these correlation factors, in particular where foundation width and depth have been varied in the same ground conditions. For this reason finite element analyses have proven to be a useful tool for performing the parametric studies required to asses factors controlling a. This paper describes the results of numerical analyses performed to investigate a factors for soil profiles which were calibrated using the results of the CPT tests performed at a dense sand test-bed site. The numerical model was first used to perform parametric 2 analyses to consider the effect of footing width, B and footing depth, D on the a factor mobilised in dense Blessington sand. In order to assess the effects of relative density, footing tests in a range of natural sands with variable in-situ densities were modeled. The results of the finite element analyses suggest that a direct correlation between qb0.1 and qc can be established at a given test site which is independent of footing width and depth and is relatively weakly dependent on the sands relative density if the zone of influence of the foundation considered is large enough.
      965Scopus© Citations 9
  • Publication
    Modelling the Cone Penetration Test in sand using Cavity Expansion and Arbitrary Lagrangian Eulerian Finite Element Methods
    (Elsevier, 2011-06) ;
    The paper considers two techniques to model the Cone Penetration Test (CPT) end resistance, qc in a dense sand deposit using commercial finite element programmes. In the first approach, Plaxis was used to perform spherical cavity expansion analyses at multiple depths. Two soil models, namely; the Mohr–Coulomb (MC) and Hardening Soil (HS) models were utilized. When calibrated using simple laboratory element tests, the HS model was found to provide good estimates of qc. However, at shallow depths, where the over-consolidation ratio of the sand was highest, the relatively large horizontal stresses developed prevented the full development of the failure zone resulting in under-estimation of the qc value. The second approach involved direct simulation of cone penetration using a large-strain analysis implemented in Abaqus/Explicit. The Arbitrary Lagrangian Eulerian (ALE) technique was used to prevent excessive mesh deformation. Although the Druker–Prager soil model used was not as sophisticated as the HS model, excellent agreement was achieved between the predicted and measured qc profiles.
      3076Scopus© Citations 91