A PRACTICAL NUMERICAL APPROACH FOR LARGE-DEFORMATION PROBLEMS IN SOIL

A practical method is presented for numerical analysis of problems in solid (in particular soil) mechanics which involve large strains or de formations. The method is similar to what is referred to as 'arbitrary Lagrangian-Eulerian', with simple infinitesimal strain incremental an alysis combined with regular updating of co-ordinates, remeshing of th e domain and interpolation of material and stress parameters. The tech nique thus differs from the Lagrangian or Eulerian methods more common ly used. Remeshing is accomplished using a fully automatic remeshing t echnique based on normal offsetting, Delaunay triangulation and Laplac ian smoothing. This technique is efficient and robust. It ensures good quality shape and distribution of elements for boundary regions of ir regular shape, and is very quick computationally. With remeshing and i nterpolation, small fluctuations appeared initially in the load-deform ation results. In order to minimize these, different increment sizes a nd remeshing frequencies were explored. Also, various planar linear in terpolation techniques were compared, and the unique element method fo und to work best. Application of the technique is focused on the wides pread problem of penetration of surface foundations into soft soil, in cluding deep penetration of foundations where soil hows back over the upper surface of the foundation. Numerical results are presented for a plane strain footing and an axisymmetric jack-up (spudcan) foundation , penetrating deeply into soil which has been modelled as a simple Tre sca or Von Mises material, but allowing for increase of the soil stren gth with depth. The computed results are compared with plasticity solu tions for bearing capacity. The numerical method is shown to work extr emely well, with potential application to a wide range of soil-structu re interaction problems. (C) 1998 John Wiley & Sons, Ltd.