The groundwater level and pore water pressure distribution of retaining excavation were analyzed based on the upper bound theorem. The work of water pressure was introduced into the upper bound work balance equation as external loading

and the Prandtl soil slip mode was chosen to analyze basal-heave stability of excavation considering groundwater level and pore water pressure changing. In addition

the effects of the groundwater level

soil strength

location of hard stratum and width of foundation pit on the basal-heave stability coefficient were discussed; and two practical cases were calculated to verify calculation formula applicability. Analysis results show that the groundwater level and pore water pressure influence basal-heave stability; and groundwater is an important adverse factor of excavation basal-heave stability. Comparing with Terzaghi’s method

Bjerrum & Eide’s method and Chang’s method

calculation method of this paper can reflect the influence of groundwater level and pore water pressure on basal-heave stability; and it provide a reasonable calculation method of excavation basal-heave stability in soft soil.