Effects of degraded durability on long-term stability for in-service slopes with RC support structures

Abstract Many engineering slope stability issues exhibit the impact of deteriorating durability on the susceptibility of slopes to failure. A thorough investigation was essential to explore the theoretical and experimental aspects of slope durability degradation and its implications for long-term stability. Hence, a durability model tailored for slope stabilization using reinforced concrete (RC) support structures was first developed here, grounded on classical durability principles for RC structures. A model test was then conducted to compare a standard slope model with a weakened counterpart, thus illustrating the effects of diminished durability on slope stability. The two slope models accounted for environmental factors, such as heavy or acid precipitation, salt spray, cyclic loading, and unloading. The test results encompassed slope surface displacements and the carbonation or neutralization (CN) depth of the sprayed concrete layer on the slope surface. These results demonstrated the enhanced sensitivity of slopes with degraded durability to environmental impacts compared to regular slopes. The empirical evidence from CN depth measurements validated the theoretical predictions made by the developed durability model in this paper, thus affirming its validity. The proposed durability model was also applied to a case study through finite-element numerical simulation with deteriorated property parameters. The simulation indicated a steady reduction in the safety factor for the evaluated in-service slope throughout its service life. The finite-element-based predictions also suggested the potential for corrosion and breakage concerning anchor bolts in this slope within a 20 to 30-year timeframe, thereby warranting timely maintenance and reinforcement actions to ensure slope sustainability in the future.