| dc.description.abstract | In recent years, global warming has made an important issue of environmental conservation and ecological restoration. The western plain in Taiwan are long and narrow, and the increase of population has led to increase of using slope land. Therefore, many ecological engineering methods have been developed in slopeland. In this study, centrifuge modeling tests were evaluated the effects of slope with vegetation on the erosion resistance and slope stability under the gravity, earthquake and rainfall conditions. Wheatgrass was to be simulated the roots reinforcement in the slope by centrifuge modeling test. This study included the element tests of quartz sand, shear strength, permeability, and growth characteristics of wheatgrass. the displacement of the model before and after the centrifuge modeling tests was measured by laser displacement transduce. The failure of the slope model was captured by cameras.
The results of the direct shear test showed that (1) the friction angle of the sample with roots increased 6 degrees, and the cohesion was increased 2 kPa. (2) The test results of the constant head tests showed that the root has no obviously change of permeability. The permeability were around 7 × 10-5 m/s; (3) The centrifuge modeling tests showed the settlement on the top of slope with root reinforcement was reduced 50% after the earthquake. The slope angle of the accumulation area increased 11 degrees, and the accumulation decreased 13%. After the test, the micro torvane test and water content test were carried out with and without vegetation slope models. It showed that the water content of the slope decreased with the increase of the height After the test, the water content of the slope surface was low, and there was almost no cohesion induced by matrix suction. According to the results of earthquake conditions, the yield acceleration of the model with vegetation is greater 0.03 g than without vegetation one, and the slope angle was also greater than 9 degrees without vegetation one. The roots had effectively a reinforcement; (4) The centrifuge modeling test by rainfall condition showed that the model without vegetation is 3.2 times than that with vegetation one. The roots could buffer the slip rate but the model with vegetation has a deeper failure surface than without vegetation one and the groundwater level raised more than 2.5 times. It was indicated that the roots could effectively erosion control, but the infiltration of rainwater will cause deeper failure than without vegetation one. | en_US |