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Longitudinal surface settlements induced by EPB tunneling in Bangkok Clay
Author(s)
Suwansawat, S.
Date Issued
December 1, 2007
Type
Conference Paper
Abstract
This research studied extensive data on ground surface settlement and shield operation collected at the MRTA Bangkok project where eight Earth Pressure Balance (EPB) shields were used. It was found that three distinct zones of longitudinal surface settlement were observed irrespective of soil conditions. Zone 1 originates ahead of the shield where the ground begins to deform. Zone 2, the largest portion of overall settlements, initiates a short distance in front of the shield face and develops largely over the shield body. Zone 3, begins after shield passing and after the tail void grouting has being performed. Operational parameters such as face pressure and penetration rate affect the magnitude of surface settlements within each zone. Large settlements found in Zone 1 are associated with low face pressure and low penetration rates. In contrast, if applied face pressures and penetration rates were very high, less surface settlements or even ground heave occurred in Zone 1. Face pressure and penetration rate also affect settlements in Zone 2 during shield passing. However, settlements occurred in Zone 3 were mainly influenced by tail void grouting. © 2007 Taylor & Francis Group.
Citation
Proceedings of the 33rd Ita Aites World Tunnel Congress Underground Space the 4th Dimension of Metropolises, 2, 921-926, 2007