The Selection of Tunneling Method and the Eventual Use of Pipe Jacking Techniques for the Installation of a Power Station Tailrace Tunnel in Machu Picchu Peru

摘要

In 1998 an existing hydroelectric power plant located at 2,000 m elevation on the Rio Vilcanota close to the Inca Ruins at Machu Picchu in the high Peruvian Andes was effectively destroyed by flash flooding caused by the melting of an adjacent glacier burying the plant with 55 M cum of material. To reinstate the plant the owner, EGEMSA, planned a new tailrace tunnel and the successful bidder elected to construct an alternative of twin 2.5 m tunnels utilizing pipe jacking techniques and a slurry TBM working from deep shafts in either valley wall Variable soils conditions and unexpectedly high jacking forces were experienced early in the first of two drives and despite measures taken pipe jacking was stopped for over six weeks. It was eventually possible, following some modifications on site, to restart the drive and successfully complete the first drive and subsequently the second drive was also successfully completed in 11 days.