Interface element method is presented to compute the stress and deformation of tower foundation by considering the construction characteristics of rock excavation and concrete constructed with different stages in actual construction.By establishing three-dimensional solid model

utilizing fast Lagrange method based on large deformation theory

and using plastic interface element considering Coulomb yield-law

the stress and deformation of concrete-rock system are accomplished for tower foundation of Jin Ping stage-I hydropower station spillway tunnel inlet.And then

its stability is evaluated.Finally

comparing with the calculation results directly considering material as solid element

some useful conclusions are obtained.The analytical results show that it is more reasonable and practical to analyze mechanical behavior of concrete-rock system by using interface element.