Vertical circular holes are often encountered in practices. The limit depth of without supporting is important for a stable vertical cylinder hole in cohesive soil. Firstly

if the failure surface is planar and pass through the slope toe

the stable limit height of the slope can be obtained by limit equilibrium analysis of vertical slope

and compared with Taylor’s results by circular sliding surface. Secondly

planar sliding surface is extended to the axisymmetric problem for vertical cylinder hole in cohesive soil. Assuming the failure surface is an inverted round estrade

and a relationship between cu /?h and h/r can be solved by limit equilibrium analysis

and provide the basis in engineering design. Thirdly

vertical cylinder hole with different geometrical parameters are numerically modeled and the lower limiting values of cu /?h are summarized. The results show that limit equilibrium method results coincided well with the numerical analysis results.