Compressive fatigue resistance and damage evolution model of foamed polyurethane grouting materials under different loading characteristics and densities

Abstract

Foamed polyurethane grouting materials are susceptible to progressive fatigue damage under traffic loads after rehabilitation for highways and railways. This work systematically investigated compressive fatigue performance, focusing on density, stress level, and loading frequency. Additionally, a fatigue damage evolution model was developed. The test results revealed lower loading frequencies, stress levels, and densities led to higher fatigue life. Stress level and loading frequency had minimal impact on the initial dynamic stiffness, which increased following a power-law relationship with increasing density. In addition, the initial dynamic stiffness was approximately 1.58 times that of the quasi-static stiffness. Adjustment, stable change, and failure stages characterized stiffness damage evolution curves. Stress level and loading frequency had a limited impact on stiffness damage evolution compared to density. At failure, stiffness damage exceeded 0.3. The proposed compressive fatigue damage evolution model, incorporating density and loading characteristics, demonstrated strong agreement with test results, with mean constitutive curve errors below 6.61 %. This work provides a theoretical basis and scientific guidance for further numerical analyses and engineering applications.