Full-scale performance testing of bored piles with retaining walls in high cutting slope

Abstract

Abstract This study aims to verify the suitability and reinforcement behavior of newly designed bored piles with retaining walls (BPRWs) for cutting-slope stabilization in the Tibet Plateau. As the first BPRWs prevention works in the alpine and hypoxic areas, full-scale performance testing is conducted of the high cutting slopes along the Lhasa-Nyingchi Railway under construction. Amid the construction processes of slope excavation and BPRWs installation, the overall structural performance, including lateral displacement, bending moment and lateral earth pressure, was determined to evaluate the cutting-slope stability and retaining mechanisms of BPRWs. The monitoring parameter distribution rules were thoroughly analysed. The relationship between the lateral earth pressure and pile displacement was studied, and a soil resistance calculation model was proposed. Finally, the BPRWs suitability was assessed. The results revealed that the retaining behaviour of BPRWs is closely related to the construction process. The displacement rate over time is characterized by alternating peaks and valleys, and the maximum displacement rate and bending moment occurs at the retaining wall pouring stage. The bow-shaped bending moment distribution with the pile depth exhibits low values on both ends and a high value in the middle. The ground reaction coefficient is allometrically attenuated with increasing lateral displacement. The proposed soil resistance model can satisfactorily predict the lateral earth pressure. The BPRWs deformation satisfies the service requirements at the construction and service stages. This case study provides a reinforcement reference for BPRW in alpine and hypoxic areas.