Methods of re-mining tunnel T08 at THSRC contract C230 after a collapse

摘要

Of the 345 km long Taiwan High Speed Rail Project connecting the cities of Taipei and Kaohsiung, the 23 km alignment on Contract C230 included the construction of 5755 m of shallow mined tunnels ranging from 137 to 1285 m in length. These nine tunnels were mined using NATM methodology. The C230 contract section runs parallel to the boundary of the Philippine Sea Plate and the Eurasian Continental Plate. These plates are converging at a rate of 7 cm/year giving rise to a seismically active fold-and-thrust belt in western Taiwan. The project is located along a very active seismic zone and passes through conglomerate, sandstone and muddy sandstone horizons of the Toukoshan and underlying Cholan Formations. In 1999, an earthquake occurred in the east central area of Taiwan registering 7.8 on the Richter scale. The event resulted in the death of about 2900 people and destruction of many structures.