Abstract: The relationship between reinforcement and soil in reinforced soil is similar to that of steel and concrete in reinforced concrete; and they share similar computation methodologies. Equivalent additional stress method can be the same with integral method or combined method depending on the equivalent method of additional nodal force calculated. Classical integral method and combined method for reinforced concrete constitute the theoretical basis of equivalent additional stress method. In turn, from the view of equivalent additional stress, the essences of the three methods, separate method, integral method and combined method are actually the same despite different stiffness matrices. The main differences lie in the distribution mode of equivalent additional nodal force on the boundaries. (In general, integral method and separate method can both be considered as combined method with special modes.) The idea of equivalent additional stress reveals the inherent principle of the three methods and can be used to interpret the reason of sameness and difference of numerical results based on the three methods in reinforced concrete. Referring to the studies of interface element, an appropriate strain ratio coefficient introduced in the integral method and combined method can make it possible to simulate the slippage between reinforcement and soil.

Key words: reinforced soil, reinforced concrete, finite element, equivalent additional stress method, nodal force