| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 94 === Due to the characteristic of soft marine clay silt is difficult to evaluate and control, it’s often a main reason of the coast and harbor engineer disaster. Because of thickness of extra soft marine clay and silt, and the properties of engineering strength are underestimated, the mound stone is sinking into seabed constantly so that the amount of breakwater mound is being insufficient seriously at the quay extension project of Fuao commercial port in Matsu county. Therefore, how to take control of the thickness distribution and mechanic behavior of soft marine clay silt is the key problem of the safety and stability of near shore structure.
In order to deep understanding the basic physic properties and mechanic behavior of soft marine soil, the undisturbed soil are obtained by maritime drilling platform in-situ and the related test were performed in the laboratory. Freeze the thin tube was adopted to diminish the disturbance of thin tube. And the simple of vane shear test was also performed to obtain the undrained shear stress during penetration drilling. This research adopts a method in laboratory to simulate the sea bed soil. And also using vane shear method obtained the undrained shear stress of marine clay slit to assess the correlation of undrained shear stress between laboratory and in-situ marine clay silt. It would be the references to inquire the mechanics behavior of marine clay silt, which can not be obtained successfully.
This study adopts extrapolation and regression method to evaluate the total mound need of breakwater base on the real mound count which provide by supervisor. On the other hand, combined with Geo-Slope program to simulate the settlement of marine clay silt, and also conjecture amount of mound by back analysis. According to the results and analysis of experiment, it can determine that seabed marine clay silt fit in with the definition of soft ground. By the result of real mound count, the designed mound count are less than the real mound count about 1.9~2.1 times. And by use of the penetration information of constructed breakwater, it could be verified the model is reliable established by this study. It is very useful and could be provided the estimated mound for related agency.
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