Particle breakage of argillaceous siltstone subjected to stresses and weathering

Particle breakage is an important phenomenon that is observed in high rockfill dams as the dam material is subjected to both weathering and stresses. This paper presents a study of the particle breakage of an argillaceous siltstone used in a rockfill dam in southwest China that is 261.5 m in height. The region is characterized by abundant rainfall and a wide variation in temperature (10–60 °C). A series of oedometer tests were performed with specimens subjected to different types of weathering. The study aims to examine the development of particle breakage of an argillaceous siltstone and the manner in which the particle size distribution of the weathered material changes over time. The results highlight that the combined effect of water and thermal weathering is a major factor controlling the disintegration of soft rocks. Particle breakage is characterized by three mechanisms: angular fracture, particle cracking and particle breakup. The weathering rate, defined as the rate of particle breakage over a weathering cycle, declines as the number of cycles increases. The ultimate particle breakage induced by weathering approaches a constant despite different axial stresses.

► Particle breakage is characterized by: angular fracture, cracking and breakup.
► Particle cracking and breakup dominate when subjected to stresses and weathering.
► Combined water and thermal weathering intensify the deterioration of soft rock.