Now，the soil between the piles is usually considered to be elastic in many calculation models of portal double-row anti-slide piles. Because of the soil being the elastoplastic material

the results of elastic models are not consistent with the reality. A new plane link finite element model is established. The soil between the piles is considered to be the elastoplastic in this model which combined the linear elastic model and the plastic model. A calculation method for calculating internal force of the fore-pile and the rear-pile is developed

which is based on structural mechanics

soil constitutive relationship and numerical method. First

the soil total stress between the piles is acquired by calculation based on the displacement of pile top used in the displacement method. Then the internal force of portal double-row anti-slide piles is calculated by numerical method

linear elastic elements and plastic elements of this numerical method

whose basic parameters are derived according to the Lade-Duncan constitutive model. Last

combining with engineering example

the internal force of portal double-row anti-slide piles is calculated with the finite element program ANSYS. Compared with the monitoring data and the calculating results of elastic model

the calculating results of elastoplastic model are more consistent with the monitoring values.