Study on the Influence of Wetting-Drying Cycle Weakening of Rock Mass on the Mechanical Behavior of Rock-Socketed Piles

Abstract

Abstract In order to investigate the influence of the weakening of the rock mass mechanical parameters on the mechanical behavior of the bridge rock-socketed pile on the slope under the condition of wetting and drying cycles, this study focuses on the sandy slate surrounding the rock-socketed piles at Luogu bridge in the Lianghekou reservoir area. Wetting and drying cycle tests were conducted to analyze the variations in rock mechanical parameters associated with these cycles, revealing the underlying weakening mechanisms. Employing the generalized Hoek-Brown criterion and finite-difference numerical simulation, the study systematically examines the evolution of the load-bearing behavior of rock-socketed piles after various wetting-drying cycles. The results indicate that, with an increase in the number of wetting-drying cycles, the uniaxial compressive strength, Young's modulus, cohesion, and internal friction angle of the rock progressively decrease, while Poisson's ratio steadily increases. Power and logarithmic function correlations between each mechanical parameter and the number of cycles are provided. The weakening of rock mechanical parameters due to wetting and drying cycles can be attributed to the disappearance of hydrolysis in hydration prone minerals and the aggregation of microscopic cracks. With increasing wetting and drying cycles, the axial force of the rock-socketed pile at the specified depth gradually increases, while the lateral frictional resistance decreases, and the resistance at the end of the pile tends to gradually increase. The total lateral frictional resistance of the rock-socketed pile shows an overall decreasing trend with increasing wetting-drying cycles. Deformation assessments of rock-socketed piles after different numbers of cycles reveal an inclination towards increased horizontal displacement at various depths and greater settlement at the top and bottom of the piles with more wetting-drying cycles.