Large-scale model tests on performance and mechanism of inclined retaining structures of excavations

The inclined retaining structure is a relatively new braceless retaining system. The existing cases have proved that its retaining performance is better, but its working mechanism still lacks in-depth researches. In this study, the retaining performance and stability of various inclined retaining structures are investigated through large-scale model tests, and the working mechanism is analyzed and revealed. The test results show that for the purely inclined pile, the earth pressure acting on the retaining pile in the active zone of excavation decreases, making its deformation and internal force smaller than those of the cantilever pile. Compared with the cantilever piles and the purely inclined piles, due to the self-supporting effect, rigid frame effect and gravity effect, the composite inclined retaining structures have smaller deformation and internal force but higher stability, and they form a rigid frame. The inner and outer row of piles respectively play roles similar to the inclined struts (compression) and the anchors (tension), making the force and deformation characteristics of the supporting structures close to those of the retaining structures with struts. The anti-overturning moment can be provided by the friction resistance in the active zone of the outer row of piles and the gravity of soil between the inner and outer rows of piles, which improves the anti-overturning ability of the retaining structures. With the same angle between the inner and outer rows of piles, the retaining performance of composite in the ward-inclined and outward-inclined piles is better than that of the composite vertical and inward-inclined piles.