Abstract: Aiming at the problem of complex formula for calculating the resultant force of active soil pressure of limited soil, based on the newly built excavations in the vicinity of subway stations, multiple limited soil failure modes are proposed based on the positional relationship between the existing subway stations and the excavations. The thin-layer microelement method is used to consider the frictional effects between the soil and the structural interface, and a method for calculating the combined force of active soil pressure is established. By adjusting the spatial position relationship between the newly built and existing structures, an active soil pressure contour map is obtained, and the parameter analysis is conducted. Furthermore, a simple calculation method for active soil pressure is put forward. The research results indicate that: (1) Five finite soil failure modes are proposed, and the corresponding formulas for calculating the active soil pressure are established. (2) As the proximity distance increases, the active soil pressure gradually increases. As the thickness of the existing subway station cover increases, the active soil pressure gradually increases when approaching the excavation, and the active soil pressure on the side far from the excavation pit first increases, then decreases, and finally increases. (3) The depth of the excavation has a significant impact on the active soil pressure, the internal friction angle has an impact on the active soil pressure, and the wall-soil friction angle has basically no effect on the active soil pressure. (4) The value of the spatial position relationship coefficient of the combined force of active soil pressure is given. Through the above research, a simple method for the combined force of active pressure of limited soil is proposed to provide reference for the design and construction of adjacent projects.