Experimental Analysis on Dynamic Parameters of Fine-Grained Sand under Multi-Level Variable Amplitude Dynamic Loading

In order to reveal the influence of fines content and load frequency on the dynamic parameters of saturated gravel sand, a series of dynamic triaxial tests on saturated gravel sand were carried out through the GDS dynamic triaxial test system to explore the development law of gravel sand dynamic parameters under different fines content and load frequency. The results show that: Under the same dynamic stress, the axial cumulative strain of gravel sand increases with the increase of fines content and load frequency, while the modulus of resilience decreases. When N=9 000, the axial cumulative strain of the FC=15% sample increases by 1.136 times compared with the fine particle content FC=0%, and the modulus of resilience is 82.06% of that of the sample without fine particles. With the increase of fine particle content, load frequency and dynamic stress amplitude, the relationship curve between dynamic pore water pressure and vibration frequency changes from peak type—steady type—growth type—decay type. The higher the fines content, the higher the load frequency, the lower the stiffness of the soil, the stronger the energy dissipation capacity, and the better the seismic performance.