PURPOSES : In this study, a numerical analysis method and the shear strength model of unsaturated soil were applied to understand the governing factors that affect the development and progress of road subsidence at various water content levels. METHODS: Laboratory testing methods, the soil-water characteristic curve (SWCC), relationship between internal friction and interparticle friction, and different numerical analysis methods used to characterize or simulate road subsidence processes were evaluated from the literature review. A contact model, and a range of interparticle static friction coefficients and cohesion energy densities to simulate the captivity initiation and progress in the discrete element method (DEM) were selected and suggested, respectively. By using the proposed contact model and values, a set of parametric studies were performed to clearly understand the progress of subsidence at various water content levels and the shear strength characteristics of soil. RESULTS : When the interparticle friction and cohesion energy density are very low, the ground particles flow like an inviscid fluid. The sequential expansion of the cavity is governed by the tangential strength of the soil around the cavity, especially when the interparticle friction and cohesion energy density are high enough. Furthermore, the difference between the quantum of flow at the outlet and the quantum of detaching particles around the cavity determines the progress and the size of the cavity. CONCLUSIONS : The parametric study using the discrete element method clearly showed the effect of the interparticle friction and cohesion energy density on the progress and subsidence of the cavity. The resizing of particles depending on the water content appears to be a reasonable consideration to create a more realistic simulation with the DEM.

ABSTRACT
1. 연구배경 및 목적
2. 문헌고찰
    2.1. 실험을 활용한 함몰 모사 연구
    2.2. 불포화토의 특성
    2.3. 이산요소법을 활용한 수치해석 연구
    2.4. 접촉모형의 특성
3. DEM을 활용한 동공 성장 해석
    3.1. 기본 가정 및 해석 조건
    3.2. 해석 결과
4. 결론 및 고찰
REFERENCES

• 윤태영(한국건설기술연구원) | Yun Taeyoung 교신저자