30 October 2008
Highway 97: test blast
Posted by Dave Petley
The latest report on the Highway 97 problem in Canada (see earlier posts here, here and here) is as follows:
- The contractor, Arthon, released a statement to the press yesterday, the key points of which stated that “Highway 97 remains closed north of Summerland until further notice due to an unstable rock mass above the highway. The slope continues to move, therefore the highway is not safe to reopen. Safety is our top priority. The ministry is doing everything it can to reopen the highway as quickly as possible, but we won’t open it until it’s safe. We’ve built access roads to enable heavy equipment to reach the slope.
Our first test blast took place this afternoon to help assess the stability of the rock mass.
The geotechnical experts will now analyze the results of the blast and will have an update tomorrow afternoon. The results of the blasting will help the ministry finalize the work plan.” - The tension crack extended by 8 millimetres overnight Tuesday-Wednesday, giving a displacement of 3.3 cm since Sunday.
- The plan to move material from the crown to the toe of the landslide now appears to be the favoured solution. It is not clear how this will affect the road.
The cautious approach beiung adopted by the authorities is quite correct in my opinion.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
November 2, 2008. According to the contractor, there was as much as 60 mm of additional movement overnight, so everyone is on high alert. Trying to buttress a mass of this size is likely not feasible. Perhaps they should try pumping lake water up into the fissure and see if they can induce a failure- that would resolve the problem once and for all.