Challenges in recent underground construction in Taiwan

Abstract

Discussed herein are the challenges met in the underground constructions of two major infrastructure projects carried out in recent years in Taiwan, i.e., Taoyuan International Airport Access MRT System and the Green Line of the Taipei Metro. Taoyuan International Airport Access MRT System is an airport link transit system connecting the Taoyuan International Airport with surrounding transportation hubs. To avoid the high risk of constructing crosspassages under water, a Double-O-Tube (DOT) shield machine was successfully adopted for the very first time in Taiwan for tunneling the section of the route under the Tamsui River. For constructing Taipei Main Station, pumping with a record high flow rate was carried out to lower the piezometric head in the underlying gravelly water-bearing stratum in order to maintain the stability of the bottom of excavation. While constructing Beimen Station of the Green Line of Taipei Metro, a historical building, which was designated as a cultural heritage by Taipei City Government, had to be temporarily relocated before construction and moved back to its original location after the station was completed. Furthermore, the shield machines in the two tunnels had to go through two SMW walls and one diaphragm wall underneath existing tunnel boxes of Taiwan Railways and High Speed Rail. Extensive ground treatment was carried out to enable openings to be made on these walls for the shield machines to go through and the H-piles in one of these walls to be removed.