| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 104 === Jakarta MRT is not only the first MRT in Indonesia but also the first large-scale underground works in Jakarta. Before the Jakarta MRT project, only limited information can be identified for subsurface soil conditions and deep excavation analyses in Jakarta. To take the advantage of Jakarta MRT project, this study aims to establish the geotechnical properties and develop 3D numerical models in order to have a better understanding of deep excavation in Jakarta. As the progress of Jakarta MRT construction, an extensive soil investigation program was carried out. The quality of soil sample are evaluated. The drained and undrained shear strength properties of Jakarta clay was determined by a series of triaxial CU and UU tests. The determined soil properties were compared with empirical relations which are correlated with SPT- N value and soil index properties. Finally, a summary of simplified soil input properties for Jakarta clay was provided. Afterward, a three-dimensional finite element model for analysing the deep excavation of MRT Bundaran HI station in Central Jakarta was developed and it is aware that said underground structure was constructed using top- down method. A series of parametric studies was conducted to evaluate the influence of soil drainage type (i.e., total and effective stress analysis), and the impact of soil stiffness on the numerical results, in particular for diaphragm wall deformation and ground settlement.
The numerical results indicated the input soil modulus has significant influence on wall performance. The wall deformation using empirical soil modulus (from SPT-N) is generally smaller than that using experimental soil modulus (from CU tests) from surface level until the depth of 8 m and reverse trends can be observed for the depth below 8 m. Finally, the results presented in this study reflected that fundamental researches on determination of sampling quality (SQD), drained and undrained soil shear strength and modulus are still in a great need for Jakarta clay because these input properties have great influences on the predicted wall performance in finite element analyses.
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