Abstract:In the elastic-plastic solution of expansion of cylinder cavities based on Tresca strength criterion and Mohr-Coulomb strength criterion, the influence of neutral principal stress is not considered. In this paper the influence of neutral principal stress on elastic-plastic solution of expansion of cylinder cavities is considered. The calculation shows that the radius and displacement of plastic zone will reduce when the neutral principal stress is considered. The conclusions are of practical significance for geotechnical engineering.