NVE: – The area would not endured additional loads – Tønsberg Blad

Today presented the Norwegian Water Resources and Energy Directorate (NVE) its report after Skjeggestad Bridge collapsed in February. The report points primarily on the work happening with Solum course that direct cause of landslide that took away the bridge.

The calculations show that the whole area was in danger to race if it were laid out more fill.

Other work was going on at the site until 2006 to have affected ground around the bridge and lowered the original safety margin. Erosion from Mofjellbekken that runs through the area pulled moreover forward. Pelvic has brought salt from groundwater below and it has formed quick clay. Precipitation amounts for January was also higher than normal for the area.

– Hardly natural cause

The report notes that it probably has been quick clay under avalanche. Although it points to a number of factors, the report concludes that natural conditions hardly have been causative.

– The research team is of the opinion that there is very little likelihood that natural processes may have caused landslide that went, it says to read in the report that NVE has posted here.

The man-made changes in the focus of much attention in the report that goes through three different periods of change. In the first period between 1950 and 1990, it has devoted a plethora of drainage pipes under groundwork with the Bakke farm. It later emerged sinkhole suggesting that these tubes might not have worked, and that they may have contributed to the erosion.

leaner safety margin

The second period that deserve attention include the actual construction period for bridge until 2006. Work on the bridge was completed in 2001, while construction of Solum course was begun the same year.

In connection with the construction was put filler in the upper area, where NVE believes that the slide has started . This reduced the so-called short-term stability in the area with fourteen percent. Thus, the margin of safety for bridge leaner.

It was also done other work with the golf course in the period, but this should not have affected security in the area.

The latest period included in the report is work going on in this area between 2014 and February this year. It points out that there were no written plans for this work.

Would not tolerated any additional loads

Here it was added large amounts of mass in the area and the location was right on the edge of the old embankment that had already made the area less stable.

– If we design the context of the same data basis should calculated the stability of the surcharges short load change there would have been that it practically would not tolerate any additional loads, the report concludes.

The report notes, however, that the area may have been more stable than the data suggests, since the filling of mass has been going on for several rounds before the avalanche went.

It has also been seen on the plant machinery or traffic has created changes in ground conditions. Neither of these two factors seem to have been able to influence the stability of the ground under Skjeggestad Bridge.

100,000 cubic meters of rock shifted, and exceeded had a width of about 100 meters. The report was prepared by NVE in collaboration with the Norwegian Geotechnical Institute, NTNU, NPRA and National Rail.

Watch the interview with Chief Engineer Stein-Are Strand from NVE in this case.