| Summary: | 碩士 === 高苑科技大學 === 土木工程研究所 === 97 === The case is analyzed by numerical simulation using finite element method (Plaxis-3D Tunnel) at South Kaohsiung Science Park in this research. It probes that the tunneling procedure adopt pipe jacking construction (PJC) with man-made excavate will meet high risk, because of the geological complicatedness and the variability of the pipeline on road. Soil improvement influences its effect very huge. If improving domain of this project is successful, PJC would be achieved with man-made. But to move pipelines of underground under highway are not allowed, the oblique type causes improvement effect inconsistently. This situation is apt to form the different effect of soil property, interface and waterline; then the risk is not under control. Soil collapse, infiltrate and the situation of sand flows will occur in case PJC with man-made takes long time due to not really filling-up with the slippery material in the gap. Probably these conditions will result in traffic jam in the highway.
The main parameters of numerical calculation in this research include advancement size, soil improvement ratio and void contraction ratio, etc. Displacement and stress distribution are obtained during calibration. The assessment of security is based on the results, including ground movement, settlement at crown and heave at invert of tunnel excavation.
Appling numerical simulation to analyze pipe jacking construction (PJC) with Plaxis-3D Tunnel in this research, it finds that excavation using PJC with man-made is safe while gap closure less than 38mm. In fact the gap closure under PJC with man-made reachs100~150mm, and it will result in high risk. Therefore, it is evidenced that PJC with shield will be adopt through monitoring ground settlement, and its security demonstrates.
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