Recent massive incidents for subway construction in soft alluvial deposits of Taiwan: A review

Since the prevention and mitigation of man-made hazards have been deemed to be the key in developing sustainable infrastructure during rapid urbanisation. Recent four massive water leak incidents taken place throughout subway construction in the soft alluvial deposits at Taipei and Kaohsiung, Taiwan, respectively, were reviewed and analysed in this study. The water leak incidents are initiated by the piping either through vertical joints between adjacent wall panels or through the seepage-prone weak zones within soilcrete body. The running leak can be traced using the variation in the piezometric pressure, and similar but smaller variations can also be seen from the soil layers at shallow depths. Lessons learned from this study would be useful in ensuring the highest quality on joints for diaphragm walls and mitigating the effect of ineffective overlapping of jet-grout columns on the watertight effectiveness while digging sump pit or dealing with tunnel-station interface.