Underground 3D Scanning in Bhutan

摘要

In 2008, the governments of Bhutan and India committed to working jointly on the development of a multi-billion-dollar hydroelectric project in Bhutan's Punatsangchhu region, along the river of the same name. With an original completion date of 2020, the entire endeavour would generate 10,000MW of power and supply electricity to millions of homes in Bhutan and India.The two governments set up the PHPA, an autonomous body involving organisations from both countries, to work on the massive undertaking. The centrepiece of the second phase of the project (called Punatsangchhu-Ⅱ or 'PHPA-Ⅱ') would be a dam of 86 metres high and 213.5 metres wide at the top. A series of tunnels, desilting chambers, surge and pressure shafts and an underground power station would be constructed, extending several kilometres from the dam site.Excavation of a downstream surge chamber in the power station complex encountered a subterranean shear zone which resulted in a roof collapse in the main tunnel, leaving it completely blocked. This delayed the project for 1.5 years while PHPA evaluated the risk and determined how to proceed. The unplanned postponement created cost overruns and disruption to the proposed start of power delivery to customers.