Hayate Seino

Examinationon direct observation of soil particles and seepage flow in the internal erosion phenomenon

Ohtsuka Satoru,Miyaki yasuyuki,Fukumoto Yutaka

One of the factors affecting civil engineering structures such as dikes is internal erosion, and it is known that 30 to 50% of the cause of damage is internal erosion. Therefore, the improvement of safety for internal erosion is also an important issue. Since the occurrence and progression of internal erosion are unsolved from the lack of direct observation of the internal conditions of the soil, it leads to the improvement of disaster prevention measures by directly observing the behavior of internal erosion. Although the analysis technology progresses, and the analysis of the progress process such as piping which is the cause of the internal erosion is expected, it is necessary to direct observation by the experiment because it lacks reliability only by the analysis. In this study, we investigated the experimental method to make the model equipment which can experiment easily, and to observe the state that the internal erosion occurred and progresses directly.
The internal erosion was classified into various erosion types by the mechanism of the outbreak, but the experiment focused on the erosion phenomenon called contact erosion. No research or experiment has been conducted for the contact erosion phenomenon, and the cause of the problem is unknown. The purpose of this study is to examine the method of observing the movement of soil particles directly, and to grasp the erosion characteristics of contact erosion in the first stage. In the direct observation of the seepage flow, we experimented with PIV measurement using a refractive index matching visualization technique. We consider whether direct observation of the flow velocity by piv measurement is appropriate.
Experimental results show that it is possible to directly observe the behavior of soil particles by the contact erosion phenomenon in the developed small model equipment, and it is possible to direct observation of seepage flow by PIV measurement.