| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 102 === ABSTRACT
Jet grouting is the most commonly used ground improvement method for the underground construction in Taipei city. However, the quality of the jet grouted columns is sensitive to the factors such as jet grouting practice, subsoil conditions, experience of contractor etc. To have a better control on the diameter of jet grouted column, this research uses a digital acoustic monitoring system to constantly monitor the sound generated from the jet cutting process of jet grouting method. Full scale field tests of this acoustic monitoring method were carried out in Japan as well as in the Southeast Asian region to account for the influence of changing geological conditions. The acoustic data gathered from the full scale tests were used to establish the relationship between jet cutting distance and recorded acoustic data on the diagram. The actual diameter of jet grouted column was checked by open cut method. Where the open cut method is not feasible, a jet cutting diameter prediction model obtained from literature was used instead. The suitability of the cutting diameter prediction model was verified by other open cut cases collected in this research. Using the relationship curves on the diagram, a critical curve for the jet grouting generated acoustic data can be established. When the acoustic sound at the recording location is above the critical curve, it indicates the jet cutting is effective and a jet grouted column with corresponding diameter can be form. If it is below the critical curve, jet grouted column with corresponding diameter cannot be form. This critical curve can be used to real time checking the effective cutting distance of the jet grouting method.
Key Words: jet grouting method, cutting diameter prediction, acoustic monitoring method
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