| Summary: | 碩士 === 淡江大學 === 土木工程學系碩士班 === 100 === Slope stability problems have been studied considerably in the past years. Relevant design codes and specifications were established based on the learning. In engineering practice, more people use FDM or FEM analysis while the physical modeling becomes more attractive for particular research studies. In this paper, 2D FEM analysis was conducted using computer program PLAXIS. Numerical examples of a homogeneous earth slope (10m height and 30o inclination) were studied extensively for the design earthquake acceleration (0.29g) under a return period of 475 years in Taipei. Considering the geographic and geological conditions of the local seismic stations and with the past significant earthquakes into the measurement, the acceleration time histories recorded at a particular seismic station located at Chungho District in New Taipei City were calibrated to target PGA for the inputs. Varying the PGA, the soil parameters and the slope geometry, the maximum horizontal displacements of the slope were computed and compared to make the observations and discussions. Slopes with and without the building on the top or at the toe were studied to see their interactions. In general, it is found that local Design Specification on minimum distance of the building from a slope is appropriate for the seismic concerns. Potential defects will be discussed with more elaborations.
The observation are summarized as follows：(1) Before the slope collapsed due the earthquake, the maximum displacement will occur on the slope surface where the crest displacement is also found critical. (2) As the slope angle increases, the maximum displacement of the slope will move to the crest. (3) By changing the height of the slope with the same inclination angle, the displacement will increase. (4) A building around the toe will not affect the response very much, however a building on the crest will affect significantly the response especially within a certain distance, say 10m. (5) By increasing the weight and width of the building or reducing the height will reduce the building responses. (6) An excavation on the slope will make some amplification for the slope on top of the excavation, however the rest parts of the slope are de-amplified. (7) If a building is built behind the man-made (say retaining wall exist) slope, the construction will enlarge the slope displacements. (8) The height of excavation or the retaining wall is important, its increase will make the slope responses worse especially for slope on top of the excavation. (9) With the same amount of soils in the excavations, the lower the excavation is, the smaller the response will be; which indicates that when making the land developments on the sloping ground, the higher the location is, the more attentions must be paid.
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