Analytical Solution of Cylindrical Cavity Expansion in the Construction Process of Pipe Pile

The problem of the cylindrical cavity under axisymmetric constraint under plane strain conditions is analyzed. The soil is considered an elastoplastic material. The physical properties of soil are described. A proposed constitutive equation is adopted to describe the stress-strain relationship for soil. The soil strength characteristics are described by the united strength for spatial mobilized plane and Lade strength criteria. The analytical solution of critical plastic pressure in the cylindrical cavity can be obtained by solving the analytical elastic equilibrium equation. The stress ratio and the relation between the critical radial stress and the volume strain corresponding to the peak stress ratio are analyzed quantitatively. The results show that the critical value of the radial stress decreases with the increase of the peak stress ratio corresponding to the volume strain in the soil with a small amount of shear dilatancy. The critical value of the radial stress decreases first and then increases with the peak stress ratio of the corresponding volume strain in the soil with an intermediate amount of shear dilatancy of the volume strain. However, for soil with a large amount of dilatancy and shear strain, the critical value of radial stress increases monotonically with the peak stress ratio corresponding to the volume strain.