Effect of Filling Humidity on the Propagation of High-Amplitude Stress Waves through an Artificial Joint

The purpose of this article is to further investigate the seismic response of an artificial filled joint under high-amplitude stress waves considering the effect of filling humidity, following our earlier work on dry infill. A steel split Hopkinson pressure bar system is utilized to induce high-amplitude stress waves to the filled joint. In this study, the wet infill is a mixture composed of quartz sand, kaolinite clay, and water. It is found that when the water content is relatively low, i.e., 8.25 %, the seismic response of the joint with wet infill is similar to that of the joint with dry infill, as shown in the literature. When the stress wave amplitude increases, the infill is progressively compacted and the transmission coefficient increases. However, there exists a crushing deformation stage for the infill in which many particles are crushed, and the transmission coefficient decreases as the incident wave amplitude increases. The water in the infill can reduce the friction between grains, which may lead to the decrease of the joint stiffness. As a result, the transmission coefficient is smaller than the case with dry infill under similar loading conditions. When the water content is moderate, such as 16.75 %, particles are very difficult to crush and the infill dominantly experiences compaction even when loaded by very high-amplitude stress waves. Consequently, the transmission coefficient through the wet infill always increases with the increase of the incident wave amplitude. When the infill is fully saturated (water content = 25.0 %), it can only experience approximately elastic deformation, and few particles can be crushed. In this case, the transmission coefficient is independent of the incident wave amplitude. When the infill is dry or fully saturated, the transmission coefficient is insensitive to the amplitude of the incident wave.