TWO-DIMENSIONAL NUMERICAL ANALYSIS OF WAVE-INDUCED INSTABILITY OF ARTIFICIAL SHALLOW COMPOSED OF DREDGED SOIL

The stability of superficial soil of an artificial shallow composed of dredged soil is investigated using a coupled fluid-sediment interaction model. Numerical results computed using the model show that surface profile change of the shallow relates to large values of the mean Shields parameter, and suggest that the stability of the superficial soil can be assessed using the mean Shields parameter. It is also found that the relative vertical effective stress ratio (RVESR) in the surface layer of the shallow rises close to unity especially near the breaking point, resulting in an increase in the fluctuation of the Shields parameter. From this result, it is demonstrated that the stability of the superficial soil is overestimated unless the RVESR is taken into account in the Shields parameter. In addition, a protection layer composed of coarse materials covering the surface of the shallow is an effective countermeasure to improve the stability of the superficial soil.