Challenges and Sustainability-Based Solutions of Diaphragm Wall Construction for LG06 Underground Station in Taipei MRT

Diaphragm wall was adopted for the subsurface excavation for LG06 underground station, one of the Wanda line stations in Taipei MRT, and it encountered many geological challenges during construction. The geological conditions in this zone are mostly clay and hard rock layer. The unconfined compression strengths of the extremely hard rock samples were tested during construction. The results were far beyond that obtained during site investigation, and hence is a big challenge for constructing the diaphragm wall. Furthermore, the Tai-power 161 kV high-voltage power cable box is longitudinally crossing the entire station zone. It leads to great difficulty during the construction of diaphragm walls. The neighbored houses are very close to the job site and cause a high risk of diaphragm wall construction. Engineers must find the solution to protect the Tai-power cable box and the adjacent houses to prevent any disasters. This paper presents how the borehole drilling method was adopted to conquer the complicated rock problem for diaphragm wall excavation. Engineers proposed a unique method by moving the rebar cage horizontally to avoid damaging the 161 kV power concrete box. Besides, a series of grouting piles with reinforcing bars were installed before excavating guide ditches for the diaphragm wall. With the innovative mitigations, the challenges, as mentioned earlier, have been mitigated. Sustainable construction technologies were successfully executed for the diaphragm wall of the LG06 station project, Wanda line of Taipei MRT.