Abstract:Under seismic loading, sliding bands originating from landslides are usually composed of coarse and fine grains.The dynamic features of sliding-band soils and the development of dynamic pore water pressure during the cyclic loading process are extremely important to the stability of slopes.Dynamically cyclic triaxial tests on gravels including fine particles smaller than 0.5 mm were conducted to investigate the influence of fine particles on the dynamic pore water pressure features of these mixed soil gravels of 6~20 mm.Three groups of specimens with fine contents of 0%, 20%, and 40% were tested using a triaxial dynamic apparatus wherein the consolidation confining pressure was 100 kPa, the ratio of consolidation was 1.0, and the frequency was 1.0 Hz.Dynamic axially cyclic stress of 0.50 kN, 0.55 kN, 0.60 kN, and 0.65 kN was applied to each group.The specimen shape was cylindrical, and the specimen size was 100 mm × 200 mm.The dry densities of the specimens with fine contents of 0%, 20%, and 40% were 1.605 g/cm3;1.741 g/cm3, and 1.570 g/cm3, respectively.After the tests were concluded, the development of dynamic pore water pressure and its evolution laws were obtained and analyzed in detail. It was experimentally determined that under the same dynamic load, a more rapid increase in dynamic pore water pressure occurs when the fine soil particle content is small;when the content is high, the speed is lower.For the same fine grain content, a small dynamic load resulted in a low speed increase of dynamic pore water pressure; when the dynamic load was high, the increase was rapid. Moreover, a larger dynamic load and smaller fine grain content resulted in relatively larger dynamic pore water pressure of soil specimens that tended to be stable.The number of the dynamic cycles was largest (smallest) when the specimen with fine content of 20% (40%) was wreck.At the end of the experiment, the pore water pressure of the soil specimen was close to the consolidation confining pressure with fine contents of 0% and 20%.For the specimens of 40% fine content, the pore water pressure was close to the consolidation confining pressure under a high dynamic load.