Underground Singapore 2011 3.2. Design Methodology The analysis for the upper connection tunnel SCL lining was carried out using plain frame analysis by computer program Staad.pro. The lining was modelled as beam elements and the ground bedding support to the lining was modelled using radial uni-directional (axial) compression–only springs, along the beam elements. Total of four analysis sections along the upper connection tunnel were selected in order to carry out plane frame analyses, which considered different load locations at which the diaphragm wall would transfer to the shotcrete lining:
Section 1 – Loading from diaphragm wall apply to lining at 45 degree direction
Section 2 – Loading from diaphragm wall apply at crown of tunnel
Section 3 - Loading from diaphragm wall apply at crown of tunnel plus pile loading of PI-9
Section 4 - Loading from diaphragm wall apply at 45 degree direction plus pile loading of PI-10
For each analysis section, two types of geometrical section considered in the analysis: 1) Full circle lining – long term case after construction works completed 2) Half circle lining – short term case during construction, in order to simulate the top heading excavation.
Figure 6–Analysis Sections along the Connection Tunnel
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