Impact of natural environment on sand aging under static and dynamic conditions

Aging is a phenomenon that affects the strength parameters of soil. This paper aimed to examine the time-dependent behavior of static and dynamic parameters of sands stored under natural conditions using static and cyclic simple shear tests. The goal was to better understand the effects of aging on shear modulus, damping ratio, and friction angle of sands with different gradations leaving under natural conditions up to 12 months. At each 3-momth interval, each sand was remolded with the relative density of 60% in simple shear apparatus in the dry state. In this research, two coarse-grained sand, one medium-grained sand, and one fine-grained sand were used. The findings demonstrated that the static and dynamic parameters of sands underwent significant changes due to aging. The friction angle, shear modulus, and damping ratio of sands decreased over time and at the end of 12 months, though they were experiencing some fluctuations. The maximum friction angle decrease pertained to medium-grained sand and was about 12%, while the minimum rate of about 1% pertained to fine-grained sand. After 12 months, the minimum decrease in damping ratio pertained to coarse-grained sand and was about 30%, and the maximum damping ratio decrease of 39% pertained to medium-grained sand. The maximum shear modulus decrease pertained to fine-grained sand and was about 22%, and the minimum rate to medium-grained sand was about 5%. Aging was found to have positive effects on fine sands under static conditions during one year of the study. Overall, over 12 months, aging showed a positive effect on the static shear strength of sands and a negative effect on their dynamic shear strength.