Expansion of Cavities in Infinite Soil Mass

A general solution is presented of the problem of expansion of spherical and cylindrical cavities in an infinite soil mass. The soil is assumed to behave as an ideal elastic-plastic solid, following the Coulomb-Mohr failure criterion and exhibiting volume changes in a plastic region surrounding the cavity. Beyond the plastic region the soil is assumed to behave as an isotropic, linearly deformable solid. It is shown that the principal parameters affecting the ultimate cavity pressure are: the initial ground stress, strength and volume change characteristics of the soil, and the rigidity index of the soil (defined as the ratio of shear modulus to initial shear strength). Numerical examples show the use of the derived solutions for computation of ultimate cavity pressure, evaluation of pressuremeter tests and computation of pore-water pressure caused by pile driving.