Mechanical behavior and design methodology of retaining structures with raked struts for excavations

Retaining walls with raked struts, which rely on the synergistic interaction between inclined rigid composite piles and retaining walls, offer notable advantages such as ease of construction, resource, conservation, and reduced construction costs. As a result, this support system has been increasingly adopted in large-area excavations. However, existing studies on the mechanical behavior and influencing factors of retaining walls with raked struts remain limited. In particular, a rational calculation method for the equivalent horizontal stiffness of raked struts is still absent, which restricts their application under complex environmental and geological conditions. In this study, finite element simulations are conducted to investigate the behavior of retaining walls supported by three typical systems: steel pipe-cement soil composite pile raked props, steel pipe pile raked props, and conventional horizontal steel pipe struts. The results indicate that, compared with traditional horizontal supports, the use of raked struts leads to a significant reduction in the bending moment of the retaining wall, a noticeable increase in the displacement at the wall top, but a slight influence to the maximum deflection. Based on extensive parametric analyses, a fitting formula for the equivalent horizontal stiffness of raked props is proposed. Furthermore, a simplified analytical method for predicting internal forces and deformations of retaining walls with raked struts is developed and validated through an engineering case study.