Investigation on the Large-Deformation Instability Characteristics of Solitary Boulder Slopes by Material Point Method

Granite rocks are subjected to exogenic forces, such as tectonic stress and chemical weathering, which cause them to weather differentially, forming boulders that are common in temperate and humid regions. The presence of a large boulder on a slope can significantly impact slope stability, resulting in the formation of what is known as a solitary boulder slope. This study is dedicated to investigate the large-deformation instability characteristics of such slopes. In pursuit of this objective, our study first validates an adapted material point method through laboratory experiments. Subsequently, utilizing the inverse discrete Fourier transform theory, boulders with varying shapes were synthesized and further transformed into material point method models. Finally, the material point method was employed to analyse the impact of boulder position, shape, and incline on the large deformation characteristics of the slope. The results show that: (1) The closer a boulder is to the plastic zone of the slope, the stronger its reinforcement effect on the slope. (2) As the shape of boulders becomes more complex, the run-out distance of the slope tends to decrease, but the variability in run-out distances increases. (3) The slope plastic zone moves around the boulder, and its distribution undergoes alterations based on the boulder's shape. This study investigates the instability characteristics of large deformation in boulder slopes with varying boulder shapes, which provides a reference for the stability assessment of solitary boulder slopes.