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This study investigated the effect of vegetation plant roots on the stability of the cover slopes of solid waste landfills. A large direct shear test and a root tensile strength test were conducted to quantify the effect of rooted soil of revegetation plants on the increment in shear strength of the soil as a method to protect the cover slope of solid waste landfills. In the large direct shear test, an increase in the shear strength of the ground with the presence of roots was observed, and the root reinforcement proposed in the literature was modified and proposed by analyzing the correlation between the root diameter and the tensile strength according to water content. The stability of the slope revegetation of a landfill facility, considering the root reinforcement effect of revegetation, was calculated by conducting a slope stability analysis reflecting the unsaturated seepage analysis of rainfall conditions for various analysis conditions, such as the gradient, the degree of compactness, the thickness of the cover, and the rooted soil depth of the landfill facility.

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Small dams managed by local governments in the Republic of Korea are facing operational difficulties owing to problems such as a decrease in the long-term storage capacity because of sedimentation and leakage, acceleration of aging, rapid lowering of water levels with seasonal rainfall and water usage, and the resulting deterioration of the overall integrity. However, the public demand for small dams has increased sharply for various purposes, especially flood and drought control. This paper presents a developed model for evaluating the condition of small dams using an analytic hierarchy process. Seventy-five earth dams in a province located in the eastern part of the Korean Peninsula were chosen. Three major components of dams, i.e., embankments, spillways, and water intake facilities, as well as the overall condition of the dam system, were evaluated. The usefulness of the improved model and its differences from the existing method were verified using the t-test. The improved model was found to be relatively simple and easy to apply in practice, and it enables on-time action for further treatment or reinforcement.

In this study, series of experimental test were conducted on geocell type of reinforcements for its imple mentation to improve the strength of soft ground. The ground for test pit has less tensile strength than normal ground, which causes problems like subsidence of ground or weakening of bearing capacity. From the series of lar ge soil box with geocell experiment varying filling materials and geocell shapes, the effect of geocell shape and filling material characteristics on bearing capacity of geocell reinforced soil layers was evaluated. Based on the result, reinforcement of bearing capacity and stress distribution effect of the sub-ground according to increase of loading was analyzed under the conditions including height, width, and shape of geocell, and types of filling materials. Evaluation of bearing capacity based on a large soil box test suggested that the ultimate bearing capacity with the maximum reinforcement increases by four to eight times in comparison with natural ground, and the largest ultimate bearing capacity is given in geocell shape of 1:1.2 (width: height) which is filled with sand, and to be 1:0.8 (width: height) when filled with sedimentary clay. Also, the maximum earth pressure in reinforced ground decreases 50% up to 60% in comparison with unreinforced ground because of dispersion of lower stress.