Numerical evaluation of uplifting effect for upper structure by grouting

A stratum grouting-soil-structure interaction model which simplified the grouted zone into a series of spherical grout bulbs was established using FLAC3D program. The hypothetical non-uniform expansion process to reach an assigned volume strain due to soil compression by grouting was achieved by imposing radial velocity on outer mesh nodes of these spheres. This new method avoids the repeated trial calculation needed in the traditional method which applied a fictitious expanding pressure in the grouting element. The deformation and additional internal forces of structure were investigated during each grouting strategy and the influences of various stiffness of grouting proof curtain and bearing capacity of pile tip were discussed simultaneously. The numerical model is proved to be effective to replicate general behavior expected in the field and is capable of modeling the uplifting effect for the surface structure by grouting.