| Summary: | 碩士 === 中華技術學院 === 土木防災工程研究所 === 97 === Taipei Metropolitan is located in an isthmus environment. Under such high density development of commercial buildings and due to an increasing number of underground adjacent structures in close proximity of constructions, an immense number of impacts have been brought on the building constructions along the Mass Rapid Transit (MRT) lines. In the past, most scholars in Taiwan have conduced studies with preference on discussing the impacts of the direct pass-through of MRT below the existing buildings, however with only few scholars provided studies on impacts of the deep excavation process for building foundation on MRT tunnels. Therefore this issue merits further investigation.
The study emphasizes on the case study of MRT project along the Xinzhuang Line, with reference to measurements taken from the 『impact assessment report of new building excavation on MRT tunnel safety 』 to be used as raw data, applying with numerical back analysis to analyze the overall displacement, lateral displacement, bending moment, and shear force of diaphragm wall, as well as vertical displacement, lateral displacement, bending moment and shear force of MRT shield tunnel during the excavation phase. Subsequently conduct simulation on the impact of foundation vertical excavation, diaphragm wall thickening, increase of supporting prestress and change of supporting stiffness to the neighboring tunnel within a reasonable range.
From the analysis results we have drawn the following conclusions: 1. The center offset△r of uplink tunnel will expand with the increase in depth of excavation of west wall SID2. 2. The value of the dump tube degree for west wall SID2 will result in a relatively reduced effect with increase for δmax in depth of excavation. 3. The value of center offset△r of uplink tunnel will result in a relatively reduced effect with the increase in depth of excavation. 4. When analysis the wall thickness of △Xc and △Yc, △Xc increases with the increase in depth of excavation, while △Yc reduces on the contrary. With respect to supporting prestress, both △Xc and △Yc reduce with the increase in depth of excavation, while the supporting stiffness remains unchanged.
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