Particle breakage and permeability characteristics of high dam rockfill under different vibratory compacting conditions

In the domain of high earth and rock dam engineering, the particle breakage and permeability characteristics of rockfill materials are important indicators that affect the physical and mechanical properties of dam materials. The quality control of rockfill materials post-vibratory crushing treatment is paramount for the construction of rockfill dams. A comprehensive study of the particle breakage and permeability characteristics of rockfill materials after vibratory compacting is, therefore, of the utmost importance. Indoor vibration tests were conducted on the scaled-down rockfill materials of the Yulongkashi Hydropower Station to investigate the particle breakage characteristics of rockfill materials under different vibration times. Laboratory constant-head penetration experiments were designed to measure the permeability coefficient of rockfill materials after vibratory compacting. The effect of varying vibration times on the change of permeability coefficient of the rockfill materials was analysed. A three-dimensional structural model was established based on the particle size distribution curve. Subsequently, a simulation of seepage was conducted on the model. Changes in the pore structure and permeability characteristics of rockfill materials under different vibration and compacting durations were compared. The results of indoor tests and model simulations were compared to validate the conclusions obtained from the indoor tests. Finally, some parameters affecting the permeability coefficient were subjected to fitting analysis, and the calculation formula of the permeability coefficient was obtained. The research results indicated that under the influence of vibration and compacting, the particle size distribution curve of the rockfill materials became smoother and the particle arrangement became more compact. After vibration compacting for four minutes, the porosity of the rockfill materials decreased from the initial value of 42% to 15%-17%, and the permeability coefficient decreased from 0.162 cm/s to 0.08-0.09 cm/s, and water flow within the pore structure slowed down. The established three-dimensional structural model well reflected this process.