| Summary: | 碩士 === 淡江大學 === 土木工程學系碩士班 === 96 === The stability of soil slope is reinforced by the vegetation roots. However, the root length and root system are gradually increased and complicated during the vegetation growth. In this research, Miscanthus floridulus samples were collected in various heights. The geometric of root system are measured first. The fractal dimension to demonstrate complexity of root system to counted for Miscanthus floridulus samples in different height. On the other hand, the direct shear tests of rooted-soil are performed to obtain the shear strength parameter. In addition, the samples of compacted sand with roots in different arrangements are also sheared to study the shear behavior of rooted soil. The main purpose of this research is to study the shear behavior of Miscanthus floridulus rotted-soil in different growth period.
Some conclusions are drawn as following: (1) The hyperbolic model can capture the relationship between Miscanthus floridulus geometric parameter in height and fractal parameter of root system complexity. The fractal parameter of root system increases gradually with plant height and tend to a limit value. This implies that the complexity of roots and the soil reinforcement will keep constant finally. (2) According to the relationship of root system in height and its fractal parameters, we can estimate rooted effect in different time period. (3) The root reinforcement effect in soil is positive when the roots are forced in tension during shearing movement. (4) The internal friction angle and cohesion of rooted soil increase gradually in the beginning of shearing movement of root and soil particle. Then, the internal friction angle will keep constant and the cohesion of rooted soils increases due to the root deformation by tensile stress.
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